There is a difference between ideas and people who put those ideas into practice. Marx was just a writer. Lenin or Stalin—I don’t think you can respectfully disagree about them.
Mahmoud Ahmadinejad (whose government routinely murdered gay people, among other nasty behaviors) gave a speech at Columbia University. While the speech was (rightly) protested, he was not shouted down, nor was he forced to flee from a violent mob.
