There is nothing in the PayPal Acceptable Use Policy prohibits firearms instruction. PayPal will, however, freeze an account and keep the money if they don't like a transaction. This happened to an NC CCH instructor in December 2022. The only explanation from PayPal is:
After a review, we decided to permanently limit your account as we found potential risk associated with it.
PayPal won't say what the potential risk is, probably because they don't know. It's a good guess the whole thing is triggered automatically without human oversight. The account holder has to spend a lot of time jumping through online hoops to hopefully get the issue resolved. There's no guarantee.
Evidently, if a transaction contains words like firearm, handgun, ammunition, ammo, etc., an account may be frozen and the account balance confiscated.
What PayPal should do is not allow transactions that they think violate their policy. Instead, they take the money and keep it. This is a vindictive attitude that seeks to punish people they disagree with.
Hopefully, PayPal will lose the many class action lawsuits filed against them because of this unethical business practice.