Damn, good writing must be really sparse these days that people don't recognize good character development and consistency.
He spent all his previous life thinking he was a failure. Now that his actions led up to another failure, the feeling is all too familiar for him. It's consistent with his past, his actions, his reflections and how obsessed he is with going "all out" so that, in his eyes, he can avoid failure. There isn't a monopoly in age when it comes to crying. If age is what's got people hung up, think of it this way: he's been emotionally stunted in his past life so you could think of it as never being able to express his emotions properly so he bawls out. But even that's too harsh of a standard of emotional maturity to measure someone. Anyone can cry, regardless of age, looks and, yes, fat people cry. What's so wrong about that?
He's been also focused on the goal of keeping Eris safe and getting enough money to survive everyday. It isn't out of character for him to do things that maybe considered 'grey' by some people. The author has shown immense quality of writing in the way that he depicts characters as not entirely black or white, even before this chapter. For example, as righteous as his dad is, his dad still had an outburst without listening to Rudy and hit him. In other less quality stories, that would be considered the trait of a villain and he would be painted totally evil with no hope of redemption. But it became 'grey' when it was shown that he could listen, that he would understand, albeit only after a stern comeback by Rudy.
Rudy isn't an exception to this grey treatment of the world. He makes mistakes, he's vulnerable and through his inner monologue you can see how neurotic he is toward his own decisions; if any of his decisions fell apart, of course it would affect him. If nothing else, I love how grey this world is because it feels more real, more sensible. I don't think he's "pathetic" for being that way.
I don't like stories with monoliths as main characters or have the personality of a cardboard box with overpowered powers as their only redeeming trait. "In another world with my smartphone" is a good pick for you if you like "non-pathetic, overpowered" MCs. I just hope you don't complain how boring it is.
