Why did Bill Murray hate working with McG?

McG claims that Murray at one point during production, headbutted him. And Murray while denying that such a thing ever happened, did say that "McG deserved to die" (or something to that effect). My first guess is to say that Bill Murray didn't have much respect for McG to begin with. He probably viewed him as a hack music video director for hire, plus used that silly nickname for his professional screen credit. It didn't help that Murray had by that point, well built a reputation of being a moody, unpredictable, loose canon.

https://www.joe.ie/movies-tv/groundhog-day-25-years-later-614739

https://www.mercurynews.com/2019/06/27/lovable-comedy-icon-bill-murray-was-an-abusive-drunken-bully-on-film-set-claims-richard-dreyfuss/

https://www.ranker.com/list/horrible-bill-murray-stories/jacob-shelton

https://www.telegraph.co.uk/film/what-to-watch/bill-murray-true-stories/

https://www.vulture.com/2018/06/how-harold-ramis-and-bill-murray-ended-their-feud.html

https://www.rollingstone.com/movies/movie-news/10-things-we-learned-after-a-weekend-with-bill-murray-40024/

https://www.cheatsheet.com/entertainment/lucy-liu-and-bill-murray-got-into-a-fist-fight-when-filming-the-first-charlies-angels-movie.html/

https://www.nickiswift.com/103018/strange-feud-richard-dreyfuss-bill-murray/