Initially, I wanted to reply to you and say it's unfair to judge the person as incompetent; I still think it's a bit unfair because they develop a specialized library and their choice of hosting shouldn't need to be modernized at every step.

However, reading through their response thread [0] I do think they aren't appearing particularly mature. It feels like they are refusing to characterize what is actually going on and digging in and escalating this defensive mindset.

[0] https://gmplib.org/list-archives/gmp-devel/2023-June/thread....