I wonder if Mark's a guy who is just getting sick and tired of the new normal in college sports... Parents taking to social media to slam coaches, the annual musical chairs game known as the transfer portal, etc. Couple that with a growing wave of criticism on him specifically, maybe it's just a mental health break he needed and wanted to take now...
I suspect you are right. I also think, he was struggling to get commits for next year and came to the conclusion it was time.
I have a problem with him pushing Graham into the portal, and then leaving a few days later, but who knows what the behind the scenes story was or is.