Instead sueing GPL "viral", you could have said "I would like to see Xolox under xyz license".

If developers choose a specific license among a few Open Source licenses they might have a good reason. Some licenses are less or more strict - by reason - and you can choose which fits best to your project. Often discussed, often overlooked.
Sueing one license "viral" in general is a) denying the authors intention b) arouses the impression that other license models (including copyleft/copyright/closed sourced) have a build-in indispensable advantage over GPL.
By the way, sueing GPL "viral" is very Microsoft in these days, but that is another troll tale.