Because he is working on a product that is hot and has demand from the users for new features/bug fixes/whatnot and also gets visibility on getting such things delivered. Most of us don't work on products that have that on a daily basis.
According to the discussion here, they don’t even care whether the tests are real. They just care about that it’s green. If tests are useless in reality? Who cares, nobody has time to check them!
And who will suffer because of this? Who cares, they pray that not them!
That is the case, whether the code is AI generated or not. Go take a look at some of the source code for tools you use ever day, and you'll find a lot of shit code. I'd go so far as to say, after ~30 years of contributing to open source, that it's the rare jewel that has clean code.