Because if you don't stand up for the stuff you don't like, when they come for the stuff you do like, you've already lost.
The current total of countries in the world with First Amendments is one. You have guaranteed freedom of speech. Other countries don't have that.
Freedom of speech gives you the right to stay silent.
A nice, easy place for freedom of speech to be eroded is comics, because comics are a natural target whenever an election comes up.
