I mostly agree, especially with the emphasis on teaching. The way I typically deal with this situation (and it's one I encounter almost as a matter of course w

I mostly agree, especially with the emphasis on teaching. The way I typically deal with this situation (and it's one I encounter almost as a matter of course with new people, and they all grow beyond this) is to have a high-level, in-person conversation about the code. Many professional programmers are actually quite good (whatever you think of this particular pull request) and the conversation is a chance to simultaneously de-escalate (whereas a nit-picky code review can escalate) and give them a chance to see their code anew from your perspective. Good luck!