I'm not super optimistic at this point but why should he know? He doesn't play the protagonist and he doesn't produce them either. Not even Pine and Quinto knew about the previous movies up until everyone got the news basically, and they play the main guys! If there is a fourth movie planned, Urban wouldn't know now, so this is no news. It changes nothing compared to yesterday.
As for him being happy about beyond, of course he is since he got what he demanded, and I guess he isn't supposed to be objective and recognize that what he likes maybe wasn't and isn't the best for this trek, but I can't help but feel bitterness over his "favorite movie" possibly being the end of the franchise. And I don't feel the ending of beyond is satisfying and so positive, they had done too little with these characters for me. There is so much they could've done with them and the potential of a new reality still, and we will never see it now. I just wish this reboot got a chance, a real one, to be its own thing.
The obliviousness around beyond's failure is a problem. If they aren't even honest enough to take the responsibility of their failure instead of pretending they don't get what went wrong , or can't find reasons, they already start bad and are hopeless regardless.