I probably overstated the “automatic” part of it. This is what I was referring to:
Reading that more carefully, that comes across as a one-time deal to punish toxic leavers as of that moment in time.
But it sets the precedent and establishes the applicable rule: troll groups by repeatedly dropping group in a statistically detectable fashion, and you may be suspended or banned.
The main point remains: dropping group infrequently won’t rise to the level of that.