Distilling one's "like" of a person down to their sexual preference [or skin color/religion/take on abortion/etc.] isn't exactly the best way to promote ideas and discussion, either. I am not sure if someone saying "I don't like gay people" is the best person to defend in the debate of "what is free speech?", which is what it seems like you are trying to sarcastically do here.

Note, this coworker in question didn't say "I don't think gay marriage should be an institution of the state" or some other impersonal statement that can actually be evaluated through logic. There is a distinct difference between those two types of statements. Do you think it's reasonable to defend people who say "I don't like gay people."?