Easy question, easy answer. When on hormones you're taking two pills. That means Phil would need to do two things that don't involve bitching/lying on the internet, mooching off friends, or getting/designing new tattoos. He'd have to do these two things everyday, and based on observations that is 2 more things than he's used to doing and would be too difficult.
Honestly taking meds is pretty difficult if you don't have someone to tell you to take them, and aren't used to it. I have seizures and anxiety issues and I sometimes forget to take meds that basically help me function on a day to day basis. Getting into medicine routines can be really difficult, and based on how set in his ways Phil is he'd never be able to keep up with the hormones if he was taking pills, the patch or had to inject.