This was Mick's entire life for two years, but was just another contractor Marty was (badly) juggling. One of them will have a far clearer memory of what's going on.
My guess would be Marty made promises to upper management and things fell apart due to mismanagement. If this was JUST Mick and Marty interacting without some level of outside force I doubt Marty would act this stupidly.
It all makes sense after reading Mick's statement. Chad was tasked with the OST for the original release date back in August 2019, and he was supposed to use the game music, including the parts that ended up being rejected for the game. This is why Mick was ignored for months when asking about the OST. They only went back to him in March 2020 when it was apparent that the studio is not up to the task.
What's more, the announcement of the OST has some ambiguous wording. They announced it as Mick Gordon's DOOM (2016) and DOOM Eternal original soundtracks. This stuck out to me immediately as a combination of Mick Gordon's DOOM (2016) and DOOM Eternal. Mick cites this in his medium post as Mick Gordon’s original DOOM Eternal soundtrack but I think that is (understandable) wishful thinking.