Taking the difference between an aggregator/gateway and a payment processor on board, seems to me that:-
a. the processors may be shared by other gateways so the various gateways could be knocked over like dominoes
b. the reclassification of vaping by some of the processors might be adopted by other processors at some point, with the same domino effect
c. even if the reclassification is outside of their control it does not excuse PayPal's behaviour in freezing assets without fair warning (if that is actually happening and it's not a symptom of merchant inaction)
If it's puritanism, as
@ZT thinks, by only one or two payment processors, it would be essential to identify which they are and not move to another gateway unless you know they don't use those same processors ... assuming this is transparent to the merchant.