quick disclaimer: i haven't paid enough attention to master matthew to know if it'd be worth trying to get through to him, but correct me if i'm wrong. if it looks like i'm whiteknighting him i'm doing it unknowingly
if matthew wants to interact better with people first thing is he needs to know how, but if he's clearly unwilling there's no reason to waste your energy
but believe it or not telling telling someone that they're annoying won't make them stop being annoying. they need to know (and care about) the things they do, why it's unfavored, and be offered a better alternative. you can tell someone they're stuff all you want, but don't be surprised if it doesn't magically make them not stuff
socially inept people never directly choose to be socially inept (again, believe it or not) and dissing them with no specific criticism is only going to drive them further down into social ineptness
but again, if matthew really wants to become easier to be around he needs to have an open mind (which i have not seen yet), and if he very clearly refuses to listen there's no point in wasting time on him.
sorry to unload all of this but thought i would give a more neutral opinion? ill admit sometimes i have too much hope for people and i hate it. worth a try though