That's a sound advise. You could engage in a systemic mass report on those posts to possibly flag them for removal or some such.
Now if you have certain resources such as a legal team, you can hand out a cease and desist against that competitor for libelous statements. Alternatively, your PR guy could spin that into a positive while also slagging off the competitor that started it. In fact, some brands engage in mutually beneficial mudslinging to generate traction for them and their competitor, though I doubt they'd never publicly say it is.
Anyway, yeah. Report it to the platform or mass report it within your means.
