I don't know if not doing everything ChipMixer said it was doing makes it a "scam," because they didn't actually defraud their customers of BTC. If anything, the government stole from ChipMixer users who hadn't spent their chips yet. Surely their actual work practices weren't as smart or thorough as they claimed to be, but they always paid out every last sat, despite years of handling customer complaints and dealing with more serious allegations.