He left two days after the new owner arrived. It seems unlikely that the arrival may have made up his mind to leave. Considering the way that Leeds have fucked their managers about in recent years, I can't blame him for wanting out.
No comparison with O'Neill who had his every whim and fancy catered for during his tenure, before flouncing out after being told he had to try managing the players he had signed, rather than just spending another trillion on a new batch to replace them.