Would anyone agree that the "friend" dynamic in men is very different to female close friendships?
I think it is all superficial, talking about cars, sport, going to the gym, having a pint and so on. No outpouring of their inner thoughts and problems/issues.
So it is just acquaintances mostly. Now I do realise that a lot of men have meaningful friendships, but I'm not sure they are that bothered by them much, i.e. whether they work hard to maintain the friendship.
Whether we like it or not, it is much easier for a man to pop down the pub with a newspaper and watch the footie, or have a casual conversation with strangers there. I know women can do that also, but I find it a bit awkward personally, so rarely do it.
So, no I don't think it's a red flag at all. Some people are self sufficient, and all they need is their family, wife and kids.