Did you actually read the "controversy" section?
A malicious adware media player - not related to Tampermonkey - installed Tampermonkey on your device to do bad stuff. And they could have done the same with any other userscript extension, like the suggested Violentmonkey. The wiki section even states:
This does not mean that Tampermonkey is malicious, but rather that a malicious program is utilizing a legitimate program for bad behavior
It's fine to advocate and promote open source software, but why do that with lies and slander?
Living off solar and batteries, I'd get to work fixing it.