It's not some sort of democracy, lol, it's a set of exclusive rights that are created the moment the work being copyrighted is produced.
(For a quick intro I recommend: https://www.youtube.com/watch?v=bxVs7FCgOig)
In the case of the license in question (L/GPL), it's one of the most strict ones out there, it explicitly forbids relicensing code under a different non-compatible license, like MIT; let me says that again, L/GPL EXPLICITLY FORBIDS the thing that happened here from happening.
I sympathize with the guy that spent 12 years of his life maintaining the code, thank you for your service or something, but that does not make a difference. The wording of the (L/GPL) license is clear and the original author and most of the other 50 or so contributors did not approve of this.
Nobody said you have.
>You just slap the license you want to your code and that's it.
Nobody said you can't.
>It's not some sort of democracy, lol
Nobody said it is, lol.
I'm answering to what you actually wrote, that those expressing their dislike of a project having a speicific license are "either malicious or non mentally capable enough" what licenses are for.
That's a stupid argument putting other people down with a silly strawman.
One can be perfecty capable to understand what licenses are for and still think a project made a mistake chosing a specific language, or want it to change to another (and sometimes, like in the examples I gave, the latter works too).
Take a look at the guidelines that keep this place together: https://news.ycombinator.com/newsguidelines.html