It would be pretty strange for a Tarot reader to read for someone else's kids, even *with* parental permission.
Also, cleansing rituals have nothing to do with reading Tarot unless you want them to, like your interesting associate does. She probably doesn't think it is in any way like you teaching the unsuspecting a hymn. Tarot cards and cleansing rituals are not inherently religious to the person doing them. If it comes up again, though, go ahead and be awkward. I always leave the room when people do breathing exercises and hide behind a tree during Indigenous smoking ceremonies.
I've given Tarot readings that said "I think it's about time you went back to church," and you all know how un-churchy I am.