If you think Grunge was about apathy towards politics (and other subjects) then you are mistaken. I could see why you’re saying this, IF you look at Nirvana. But let us not forget that they were not part of the grunge-wave in any other way than being from Seattle.
Seattle-rock, having its own sound from heavy metal and hardrock bands such as Alice in Chains, changed from meaning that to include all rock labelled “alternative” (even though mostly commercialized “alternativism”) from the ‘underground’ of Seattle. The same applies to ‘Grunge’ which, to my eyes, go hand in hand with ‘Seattle Rock’.
When we also know that Nirvana is nihilistic punk, hence a contradiction to bands who cared/cares for politics and the global situation (i.e. Pearl Jam), we can all agree that Nirvana can only be justified as ‘Grunge’ when you apply it the original meaning (‘(alternative) rock from Seattle’).