I consider myself straight,but not phobic--and have jerked off a few guys. I guess in a way, I can now relate to why my GF loves it...it is an awesome feeling to 'see' the fruit of your labor (a guy squirts of course)-- Mind you I have no desire to touch a guys butt, or kiss him, or any other M/M contact. I don't really find men attractive, but cocks can be... I find it funny when I see cocks on here that are hot, and then see the guy attached and don't find him attractive at all.
But as for your question..It does not make you gay at all... DO you get emotionally involved with men? any desire to do so? Gay has so much more to it than just a hand job. Consider it (your hand jobs) just a form of masturbation (which it is) and have fun with it.