Something about this example is not registering for me. I can't imagine how this situation is possible. Going from a detailed, step-by-step description to a code implementation is a trivial rote task in my mind. I must be missing something.
There's definitely tons of senior devs out there that care way more about linting and unit testing than they do about writing the code that implements the spec.
This guy couldn't deliver a single project and would spend days debugging issues before he asked for help and I or someone else on the team would solve it in a couple of hours or less. I have no idea why this happens, but I've seen it twice.