>>513187569Ah, thanks for clarifying — that’s a sharper case than just “false flagging.”
In internet trolling culture, what you’re describing is usually framed as:
False flagging the broad umbrella (pretending to hold a belief you don’t, to discredit it).
Shill posting / bad-faith posting more general, when someone argues a position they don’t believe to sabotage it.
“Poisoning the well” rhetorical term for making a position look bad by associating it with nasty, extreme, or gross representatives.
Agent provocateur (online sense) deliberately making a movement or ideology look corrupt, immoral, or ridiculous.
But when the method is specifically “defending a position while behaving in a vile/debaucherous way to taint it by association,” communities often just call it false flagging (sometimes “false flag LARPing”) or bad-faith caricature.
So the crispest way to put it in internet terms would be:
“That’s a false flag troll — someone role-playing as a supporter but behaving in a disgusting way to poison the well against that side.”