It's not just my preference, anyone familiar with this area of copyright law recognises copyleft as its standard name. Viral licensing is, as I said, a snarky pejorative. [0][1]

It's also less precise. Proprietary licenses can be 'viral' too. DRM libraries, for instance, may require that application source code not be made publicly available.

> At the risk of seeming pedantic

Parroting others in this way comes across as juvenile and antagonistic.

[0] https://en.wikipedia.org/wiki/Copyleft#Viral_licensing

[1] https://en.wikipedia.org/wiki/Viral_license