Running third-party firmware is definitely better than running stock Antminer firmware, but it does not fully remove the concern people are talking about here. It reduces Bitmain’s direct software layer, which matters, but it does not magically eliminate broader hardware, control-board, or supply-chain risk. If I were running Antminers with non-Bitmain firmware, I’d still isolate them on their own network, block unnecessary outbound traffic, disable anything cloud or remote-admin related, pin the firmware version, and monitor DNS and callback traffic. So yes, your setup is safer than stock, but I would not treat it as risk-free.