It wasn't a request - it was a question - "do you play a Fender?" - if he asked "would you play a Fender?" and it was a good enough gig to warrant acquiring specific equipment than it would be totally valid and it would be the OP who would be wrong if he said "no."Why is everyone up in arms when a bandleader requests a certain brand / instrument? "You're better off not playing with them." is the common response. No you're not, you didn't get the gig because you didn't meet the bandleader's request. I've been pretty lucky with open mindedness with bands, but if someone makes a request, I'll meet the request and maybe bring along another bass that I'll suggest that we try at some point. I just don't see the point in shooting yourself in the foot at square one.
I will state that I personally believe that any serious player should have something that can at least pass for a P, but to turn someone down without knowing who they are or how they play is stupid, period. Again, if the bandleader wanted a specific instrument after auditioning the player, then he could make that request and you are right in saying it's his right to desire something specific, but you need to know how the person plays, not what they play - there are lots of guys who own Fenders who suck and lost of guys who can only afford an off brand cheapy who absolutely rock - so ending an "interview" after that question is what iis stupid - not having specific wants and desires.