Again not necessarily, I have often wondered about the ability to detect rootkits on a boot-time scan, given that some of them may not yet be active. Why else would avast run its default rootkit scan 8 minutes after boot ???

One of the ways of detecting rootkits is to compare what is actually running against what the Windows API reports as running, so this particular method may not be available, depending on just what has loaded in windows at the time the boot-time scan kicks in.

So this really isn’t clear cut.