Yes, they are. You can distribute flyers, solicit donations, panhandle, parody, and impersonate in a physical town square. You can also hire agents to do all of that for you. And thanks to the (highly questionable) doctrine of corporate personhood, you can even do all that as a corporation and it's all protected speech.

Here's a whole gallery of people exercising free speech through impersonation in physical town squares across the country:

https://www.alamy.com/stock-photo/trump-impersonator.html

Twitter doesn't allow that. Why?