As a metaphor, it might have some rhetorical usage.
My initial point was to reply to a post that when off on claiming true mental illness. That was not useful in debate.
Being convinced of a position in spite of evidence is more a function of normal cognitive decision making processes. A good read on stupid decision making processes is Kahnemans' Thinking, Fast and Slow.
So rhetorical use of 'phobe' - I DO NOT want to start a discussion of gay rights but the usage of homophobe to describe opponents of gay marriage is equivalent to hoplophobe. A strongly held belief with some emotional components about a political position isn't as of yet a mental illness.
There are theo'phobes' - people strongly disapproving of religion. Sloppy usage - well, I'm going to load the clips of my semi-automatic assault rifle, now (