While I agree about a photographer not having to photograph things they don't want to, as someone else said, where do you put that line in the sand?
If the private business of a photographer can deny their services, can the private business of a hospital deny their services for those same reasons?
The problem is it's a hard discussion to have as on the one hand you want private businesses to be able to give bigoted folks the boot, but then private businesses of bigots can then throw you out all the same. Advocating for the first does mean unintentionally advocating for the latter.