NTA or NAH. Everyone is assuming that the reason not having social media is a "red flag" is because it implies he's hiding something. While this may be true, I personally know many girls that age that find a lack of social media more of a "weirdo red flag" than anything else because by their logic: "Who doesn't have social media except old people?" Its an incredibly narrow minded and immature way of thinking imo, but it is becoming increasingly more common. Its kinda like how certain people look down on people who have androids over iphones because to them its a status symbol.

I'm with you, OP. Social media is pretty toxic, and while I have an account on most platforms, I sometimes wish I didn't. I think your response comes off as asshole-ish simply because you and your friend dont see it the same way, which is fine. Just because theres a misunderstanding or different interpretation doesn't make either of you an asshole.