I think the acceptance by older guys depends on what kind of gyne it is. For instance, I think pseudo-gynecomastia is going to be much more accepted by your average (probably overweight) middle aged male than true glandular gyne is. For one thing, I think fatty gyne not only looks different than real gyne, but also FEELS different. One is just fatty boobs, while the other is true glandular growth. And there's a big difference in that in the minds of most guys. I think it's due to the fact that, in middle age, the rest of the body doesn't look so great either, so what difference does having fatty boobs really make? Most guys can accept fat, but not real boobs.
I also think there's a psychological difference in the minds of most guys between pseudo and true gyne. It's more accepted and expected that middle aged guys will gain weight and their chests will not look as good as they once did. But it's a whole other thing to develop female-like boobs. One is expected and even semi-acceptable, the other is not.
And finally, I think there's a big difference in the minds of most guys on whether they THINK they could get rid of their gyne if they really WANTED to. A guy "could" decide to go on a fitness program and really get in shape. And fatty (or pseudo) gyne would respond to the exercise if he chose to do it. So just BELIEVING you can do something about a problem is important when it comes to accepting the condition.
This reminds me of people who smoke. A lot of smokers THINK they could quit if they really wanted to, and that's a comforting thought (regardless of whether or not it's true). Just THINKING they can quit makes them feel better. But some smokers HAVE tried to quit and have failed. And the REALIZATION that they might not be able to quit is very problematic to them. These smokers might be much more worried about their smoking than smokers who think they could quit if they wanted to.
So I think it makes a lot of difference if men simply THINK they can do something about their fatty gyne, regardless of whether or not they ever actually try to do so.
On the other hand, as we all know, true gynecomastia does not respond to exercising or working out. If it's glandular, nothing's going to change that.....except surgery.
There's a certain comfort in the minds of a lot of guys with pseudo-gyne that they "could" get rid of their fatty gyne if they really wanted to. Whereas, the guys with true gyne know they CAN'T get rid of it unless they elect to have surgery.