While helping my son with his C++ homework I noticed there was an actual shit ton of warnings in the teacher's code.

I'm beginning to think there is some merit in the maxim, "He who can does. He who cannot, teaches."

Uhheesh.

Also we used to add: "He who cannot (teach), consults".

Teach him how to learn and be self taught because school is shit usually.

What a teacher gives out usually isn't there to work or be future-proof or whatever, but to teach a single principle. I would say that school is the only time where having a lot of warnings is ok: You write a program, talk about it, remember a few things, then delete it. Putting in extra work to fix warnings would be a waste.