The intent of trolling is to piss people off, and that's best achieved by opposing the (albeit losely defined) principles of harm reduction Meso values so dearly. 'You reap what you sow' - calling out sources or members for misinformation, manipulation, obfuscation, scamming, lying, fake labtests/reviews/products etc. in an insulting/hyperbolic manner has always been part of Meso but I wouldn't define that as trolling as long as there's reason/evidence for these callouts, and this burden of proof separates the vets (or whatever you want to call them) from the trolls in my opinion.
I think trolls should be banned by the admin's decision if they've amassed a post history fitting the above definition. Reports of trolling should be used as a note for the admin to pay attention to/review the offenders account but no amount of reports should by itself be the reason for a ban to avoid the popularity problem you mentioned.
Realistically speaking, any nuanced approach to this issue might consume more time than you have to spare.