I'm not sure I've ever seen such a vicious case of NIH-syndrome. Regardless, congrats on the solve!

Since this was for fun, and the goal was learning at least as much as solving the problem that is just fine. More people should get NIH for those purposes.

Now if he is presenting his tools as a good way to solve this problem, something you should use, or any such - that would be a bad thing. Good tools for this are complex and need to be done as part of a large team. If good tools that others should use is the goal then he should join some other group making those tools. I'm sure there is an existing open source project (maybe KiCAD - I'm not in this space so that is the only name I can come up with but maybe their goals are different?) that does this and would welcome more help.

I first thought you were teasing Jane Street instead of OP. Maybe shows that OP is a good culture fit for Jane Street :)