Time, place and manner.
Freedom of speech allows all to speak, even the degenerates. If they didn’t speak up, you wouldn’t know who they really are.
So your point is: Given the "right time", the "right place" and the "right manner", a "peaceful protest" calling for the extermination of any other minority group would -- or, rather, should, in consideration of "freedom of speech" -- be allowed to proceed. (It's early out here and I'm still on my first cup, so admittedly it's possible that I miss your point.) Cheers!