You must be new to usenet. Again, there are no admins here. There are no
moderators here. Spam has been coming from Google Groups for many years.
Your spam is someone else’s free speech.
Filter it out on your end. Or just ignore it. No one at Google is going
to “pull the plug” on anything just because you are offended. It would
take millions of complaints to Google, and there just aren’t that many
people reading this stuff these days.
IOW, just get over it. Tell Thunderbird to ignore/delete anything coming
from Google Groups. Problem solved.
Also, you need to understand that this stuff comes and goes. The people
spamming here are also new to usenet. They think that millions of people
will see this stuff and it will help their business. The fact is that
there are very few people on the planet who know that usenet even exists.
Plus, most regulars with experience are already ignoring everything that
comes from Google Groups.
Plus, this group is basically dead anyway. The result is that maybe 10
people are seeing this shit. So after a few weeks the spammers go away.