Great Mothers Unique Working for Non-NS Allies

Great Mothers unique To The Old Ways states,

 "Whenever a Vulnerable enemy begins its turn, all Nightsister allies gain Foresight for 2 turns, and all non-Tank Nightsister allies gain Stealth for 1 turn"

But this seems  to be working for Non-NS allies as well. I attached a screenshot where Non-NS allies gain stealth when a vulnerable having enemy takes a turn in this case it was wrecker in Conquest.