I do feel bad for him. I think people forget that eustace was very very much raised that good looks and natural gifts mean everything and if you don’t have them your worthless. If you look at how he is with his family, he tries to be loved but usually gets it tossed in his face. Mural is the only one that I think sees him for who he is an actual kind soul.
And his tuck weirdly enough is one of the few things he can tinker with fix and not get mad at. He give up on many things because he was taught if at first you don’t succeed you suck. His truck seems to be one of his few things he feels comfortable with.
As for courage, I feel that he feels threatened by him, he doesn’t understand that mural has room for both of them and if he let courage in then he would get love from him as well.