> If people "on the left" won't allow him to speak, where exactly do you expect him to go?

Adding to this; we should bear in mind that while nobody specific speaks for "the left"'s moral judgments, at least some people literally won't allow him to speak.

Secondly, he was never trying to be a martyr and we shouldn't expect him to be one. He was posting a controversial opinion on a message board marked for controversial opinion. He was clearly putting in a solid attempt to be objective and to employ facts and evidence. He has some academic exposure to the fields he was talking about.

He didn't expect to be targeted the way he was; he likely wasn't trying to set himself up as a hero of free speech; and he doesn't have to do a walk of shame through hostile talk shows to justify his intentions if he doesn't feel like taking the (unjustified) heat.