He's not shit at his job, he does exactly what he's told to by his boss in order to keep his job ffs. What's the point in him going against Ashley's wishes, losing his job and some other stooge taking his job? "Well done Lee, you lost the best wage you'll ever have, nothing changed because Ashley can't be changed, but at least you took a stand."
Any anger directed at him is exactly what Mike wants. It's what he's there for. Deflecting attention away from Ashley, Barnes and Bishop, the three that really run our club.