Yes, a significant fraction. My point is, physically-present operators did spot AN issue immediately. It wasn't properly attributed to malice for months, sure,

Yes, a significant fraction. My point is, physically-present operators did spot AN issue immediately. It wasn't properly attributed to malice for months, sure, but they could still mitigate during that time. Without their presence, would you (as attacker) really bother with all the stealthiness? It certainly hasn't seemed to avoid long-term attribution. Set the controller to +INF RPM and let whoever pours over the logs in the morning spit out their coffee.