When you’re responsible for supporting people who refuse to receive patches like this one [1], and those same people have the power to page your phone at 11pm on the weekend… you quickly learn how to call a spade, a spade.
There is undoubtedly a better word than stupid. They're very likely not stupid. Careless, maybe. Inept, maybe. Irresponsible, maybe. Stubborn, maybe. More generously: overworked. Just probably not stupid.
[1]: https://patchwork.ozlabs.org/project/ubuntu-kernel/patch/202...