He's not defending Trump. He's just clarifying an important point of truth.

If you have the habit of wanting simplistic ways of looking, simply because in this case it'll make your enemies look bad (even if they are, as in this case, very very bad people), you should break that habit. Sooner or later it will turn on you.

I have no idea why so many people are snatching onto this thing as a reason to say bad things about him. I sort of suspect it is because of addiction to "gotcha!" and being able to be superior to people. He made an important point unclearly, and than clarified. That's okay. It's Twitter. He's way ahead of the curve even for a normal social network, and he's been using his Twitter account to publicly shit on Trump for quite a long time. You should give him credit for also being committed to precise truth at a time when it's not very popular at all.