In all honestly I believe she uses that line for traumatized newly returned destroyers.
Cowering scared out of her mind Destroyer girl then Tenryuu walks in say her line then adds In a soft caring voice Don't be Bis sis Tenryuu will keep you safe then extends her hand slowly.
Tenryuu was Built from the Ground up to lead and Guide Destroyers her presence would radiate this. This is most likely why Destroyers not just the Dev 6 girls flock to her.
They instinctively feel safe around her.