Would it be unsafe to disable such behavior? I frequently have breaker trip on line main PC is on (which "hot" Armory is on), resulting in a rather high frequency of rescans.
Probably safe. It was in my plans for 0.91 to investigate that. It was done out extreme caution, because of risks associated with incomplete transaction histories (when the history is
close enough to correct that it looks correct, but it's actually not correct).
However, I suspect it can be done.