Early 20th century progressives supported eugenics out of a belief that it would improve society. Contemporary liberals support abortion rights and right-to-die laws out of a belief in individual rights that flowered in the 60s.
Most of all Drum is saying that the earlier history is not very illustrative of anything for today.
I view it this way. Go back to Millian liberalism of the mid-19th century. Had American or for that matter British Progressivism been infused with more of this philosophy, the eugenics debacle never would have happened. For instance if you look at the British Parliamentary debates of 1912 over the Mental Deficiency Bill, the anti-eugenics forces drew heavily upon Mill for their inspiration. This was standard stuff, but the Progressives of the time didn't see much of a pro-liberty reason for being pushed into a Millian position, quite the contrary.
The claim is not that current Progressives are evil or racist, but rather they still don't have nearly enough Mill in their thought, and not nearly enough emphasis on individual liberty. Their continuing choice of label seems to indicate they are not much bothered by that, or maybe not even fully aware of that.
I'm a bit skeptical of Drum's claim that modern progressive thought is based on the concept of individual rights, although I don't deny that this concept plays some role. However I believe utilitarian thinking plays a much bigger role. Consider the progressive views on marriage. If they were based on individual rights then you'd expect progressives would favor unlimited marriage liberty for adults. If they were based on utilitarianism then progressives might favor some marriage rights, but not others. Since many progressives favor marriage rights for gays, but not polygamy and incest, it seems to me that their beliefs are more motivated by utilitarian considerations. Drum himself hinted that he was rethinking their views on drug legalization, based on the recent Oxy epidemic. That's not an "individual rights" approach to the issue.
My thinking doesn't fit neatly into either camp. On most political issues my thinking is much more libertarian than progressive, and yet the philosophical justification I rely on is utilitarian. In my view most progressives lean left because they underestimate the costs of government policies that restrict liberty---especially in the field of economics.
Here's where things start to get complicated. Progressives are split on free speech. Do the pro-free speech progressives rely on individual rights or utilitarian reasoning? The most common justification I hear is "rules utilitarianism", which suggests that while society might be better off if certain types of speech were banned (say Nazi propaganda), society would be worse off if the government were given the authority to determine which type of speech should be banned, as it would inevitably bleed over to unpopular minority views that ought to be heard. So we should adopt the set of broad policy rules that best maximizes aggregate utility, such as the 1st amendment. I agree and indeed would have it cover most commercial speech as well.
This raises the difficult issue of how far to stretch "rules utilitarianism." One could argue that while society would be better off if wearing seat belts were mandatory, society is worse off if government has the right to make mandatory any action that they see fit to mandate. So perhaps the government should be prevented from interfering in a very broad class of individual behavior, not just speech. And I have some sympathy for this view.
But in the end I'm not willing to go all the way to a constitutional provision locking in extreme libertarian governance. That's partly because it's not clear to me where you would draw the line. Are taxes coercion? What about carbon taxes aimed at preventing externalities? I worry that the economy is too complex for any simple form of rules utilitarianism to stretch over all human interaction. In the end, we must do the best we can in each area of governance. My goal is to convince progressives that the best interests of society involve a much bigger role for free markets and individual choice than common sense might suggest. (This is not my area of expertise, readers may want to look at books such as Richard Epstein's "Simple Rules for a Complex World".)
This is one reason the eugenics story is so useful. To progressives of the early 20th century, these seemed like reasonable regulations, which would improve society. That should be a warning to modern progressives that rules that may seem very beneficial today (say a law requiring everyone be paid at least $15/hour), may be viewed as being very sinister by future generations (as a law banning millions of low productivity workers from seeking gainful employment in the legal economy, forcing them into a life of crime). This would be an ironic reversion to early views on the minimum wage, which often did have sinister overtones, perhaps even racist.
Even if people are voluntarily choosing to do X, society may want to ban X. But the hurdle should be extremely high, far higher than most progressives realize. My dad smoked his whole adult life, knowing that it was dangerous. He was very intelligent and felt it was worth the risk. He died from smoking at age 69. My stepfather smoked for decades, and then decided to stop at age 75. He's 91 and still plays handball (a very strenuous game.) For selfish reasons I wish my dad had not smoked, but we should respect both their choices.
PS. My suggestion that free speech should apply to most commercial speech may seem rather lame---why not all? I haven't thought much about this issue, but perhaps collusive speech should be excluded from protection? I'd appreciate any thoughts on this issue.