This guy doesn't think deeply about any problem, possibly because he has never had to and probably because he has never wanted to. He would probably make a good residential plumber.
Let me deconstruct it for you.
His words: He would probably make a good residential plumber. would probably make a good residential plumber probably make a good residential plumber. make a good residential plumber. a good residential plumber. good residential plumber.
And since you’re so intent on deconstructing:
> He would probably make a good residential plumber.
Him making a good residential plumber≠average residential plumber is good.