Well he does if he wants to fix those things... If, not then he sure doesn't
And it is not that hard to port a game to a different lang/engine. Way, way far easier than making it first-time. Actually, it is a matter of minutes if anything.
And anything is easier than Java (if we aren't talking assembly or such, of course)
I am not saying he has to btw, I just suggested it, and it is only one of the things I said. Not the only thing I pointed out.
But it is true that Java does directly cause a lot of problems with the game.
Why should he care? As I said, that is up to him how he treats my feedback. And as the developer, he really should care about feedback btw. He does not have to listen but should take it into account and decide if it is worth doing or not.
Seems you guys never even touched programming (Scratch does not count) or don't know what feedback/reviews are for.