Without saying anything about this particular person, I've found an interesting pattern with people who seek out a specific programming language to work in: their actual code tends to suck pretty bad. People that obsess over any particular language will typically obsess over it because they learned some new abstraction trick and seem to think that everything should be rewritten in it. And so instead of focusing on the problem they have to solve, they become obsessed with rewriting code that already has solved problems...and they tend to do it in a way that is short and succinct but utterly opaque and black-boxish. No thanks.

Again, I'm not expecting that everybody who does this is like this, but I've seen it enough that it is a pretty strong negative warning signal.