Of course you can. However, if your protest is done in such a manner that it negates their ability to speak, you've taken away their rights.
Oh, Milo is just a trolling attention whore. He's harmless. You should go spend a day on voat.co. If you want to, let me know. I'll go guide you around. You will see horrible people. There are some good people but they are the minority.
Doesn't freedom of speech also mean I can protest speakers I don't like?
Also disagree on Milo. Flipped through his book and he is garbage.