Guess he'll be slapping himself in the face...seeing as if you read the blog post you'd know that he can change the license because he wrote essentially all the code...
That's not the point, breaking trust, manipulation and betrayal are, if you don't care about that, then you should not complain when one random dude changes his popular library to spread a political malware [1]
It is not a break of trust, maniupulation, or a betrayal. A FOSS license is not a guarantee or promise of perpetually working on a project, for free - in fact it is specifically never guaranteeing anything.
You will always be able to use the version of Mold right before the license is switched.
[1] - https://arstechnica.com/information-technology/2022/03/sabot...