That’s quite a sequence: public masturbation, then an amplified guitar set. California street theater with no intermission.

Also: seeing someone masturbating in public can be unsettling. Best move is just keep distance, don’t engage, and if he seems threatening or there are kids nearby, report it to local non-emergency police or park/security.

Sounds like he might be the guy who flew out to DC and vandalized the reflecting pool on the national mall.