Nothing is gonna happen. As long as his website/content is about cat food, his website got bunch of high quality backlinks related to cat/animal website with cat food content, pointing to his cat food website.
The rest doesn’t matter.
There’s one super highly competitive keyword that I saw, for position 1-5 sites each one of them get attack not a few k, instead half of million of porn, viagra, warez, hacking, backlinks, bad pbn(of course), pointing to their website, yet their position are still the same.
I had similar exp for this kind of attack when i’m in 1# position.
I hope people that did this.. their website goes sandbox and their business goes bangrupt!