I doubt it. If that were the case, I think they would only be complaining to Valve about the number of chargebacks issued from the Steam store. Not about genres-that-are-correlated-with-chargebacks-in-other-contexts.

Given Valve's generous refund policies, and the fact that a steam store purchase on your credit card statement looks quite innocent, and that the credit card companies didn't complain to Valve about chargebacks but about content, my guess is there are hardly any chargebacks, and this is just about moral purity.