You're free to try running a payment processor with a mantra of "Innocent until proven guilty."

You'll be a honeypot for every scammer, fraudster, and con artist ready to take advantage of that policy, your processing fees will be through the roof because of chargebacks, and the only people who will use your platform will be the aforementioned scammers, fraudsters, and conmen.

I'm sorry for the GP poster's situation, but there's really no way to make everyone happy, here.