That and the big question over, if they do detect a domestic agency's APT, will they even report it? Warning: Top Secret / NoForn leaks below.
Allegedly,
- McAfee reached out to the FBI about Magic Lantern,
- Kaspersky were believed by the NSA to not detect Russian-affiliated malware,
- and I can't find any sources for this, but I remember reading about and having chats earlier in my career with folks in AV companies mulling over what to do in this situation.