[clintonwoo]

Sounds like you have a talented developer on your hands without enough experience for the business sense. Maybe for the inter personal sense also.

Sounds like a mid level developer since they have the code skills but lacking experience and inter personal skills. I myself have been in this phase once, although I achieved significant improvements in UX, performance and maintainability though changing structure.

I would say just low key ask them what's the business case or engineering justification for the rewriting. Ask them to justify the justification, just probe their process. Over time hopefully you can converge an agreement.

You mentioned his views are binary but this isn't very important. Maybe he's just being to the point or concise. A bigger issue could be if he's hurting other people's feelings with comments in which case that just needs to be brought to his attention if he doesn't realize.

All the code there was likely written by existing members of the team so criticizing that code could be taken badly by other people, well intentioned or not. Ask him to think about other people hearing somebody criticize the projects they worked on.