Seems like the usual story of some lone maintainer maintaining a popular project and losing their time and energy.
The post doesn't spell it out but I wonder if they implied there's a suspicion that the person doing the pressuring there is also another sock puppet of JiaT75 as some scheme of getting access to xz. That would seem particularly cruel; take advantage of a tired maintainer with mental health issues to use their project to smuggle security exploits to the world.
Regardless, be nice to people who are doing "unpaid hobby projects" your work depends on. Reading the thread made me sad.