Love it when random people on the internet look up the first Google result and think they know more about halachic debates than I. Hint: you don't.
Then explain why Maimonides was wrong.
He's not, but you're misunderstanding his argument. Maimonides states that the Tanakh does not ban [male] masturbation, which is true. However, the Talmud, on which Jewish law is largely based, does, and this has also been codified in the Shulchan Aruch which is nowadays almost universally considered to be authoritative.
Well that settles it. If I was born Jewish I would 100% guaranteed convert out of it. It should go without saying whether hipster Christianity has any problem with this activity.
(In fact my church seems to consider it an act of empowerment, especially for women)