Alas, it's still related enough to religion to easily lead to religious flamewars on the internet. The burden is on the commenter to pack the point in less flammable packaging. "Protestant mentality" is too generic a phrase not to have religious associations for many readers. If you said "Protestant work ethic" that would have been better, and if you had made it clear that you were referencing Weber, there would be no problem. Far fewer internet users are likely to start a flamewar against Weber.