It may or may not be.
At least the seed I've been using lasted almost 2 months, and the last time I used it I was playing quietly at the Pokemon Sun. Then I went to sleep,
when I woke up, I saw that all this happened.
I still don't understand why this seed ban was due. Many people pledged to deactivate SpotPass to be more likely to avoid the ban.
That Nintendo has seen people playing from the same seed I don't think, if it had happened that would have banned since before.