Sadly, they're not the only ones and there's plenty of similar clowns out there.
People such as this individual, who's stealing, converting and selling a number of mods from rF1 and GTR2, including (but not limited to) GTPC and SuperTouring, as well as the old TRD3 V8 Supercars which were also converted to GTR2 as a free mod.
creating mod tracks, cars for Assetto Corsa
www.patreon.com
This is just an example, but there's plenty of them out there.
AC is literally flooded with this payware garbage, with people stealing from each other and from commercial titles and nobody ever does anything about it. And the cold truth is that plenty of that stuff is still indirectly being supported right here at RD. Hundreds of skins are being uploaded on a daily basis for dozens of these mods. All the Rollovers mods featured either stolen models from Raceroom or rFactor 2 and GTR2 just to name some.
Plenty of other mods scattered around all feature stolen models from Real Racing 3, rFactor 2, Gran Turismo 6 and Sport, Forza Motorsport 7 (and below/above given it's multiple titles from the same franchise) and many more.
Highly regarded mods from Bazza or SBH are great and all, but despite them being free they all feature content converted from GTL (both from Simbin and other mods), P&G (a GTR2 mod), HistoriX (an rF1 mod) and GPL.
Literally dozens of skins are being uploaded daily for "AC mods" that are actually ACC conversions.
RD is far from being "very careful about not tolerating piracy". Granted it's technically not your fault, something needs to change in the process for submitting a new mod to your website, especially given how easy it is to fool the system and the average user that doesn't know better.