Still good on him for honoring the purchase even if he gripes a bit about it.
As proprietor he has every right to deny the 'cheating' and even get the two removed from the store not because of their species but specifically because they have this kind of capability, but good on him for putting up with it.
Good on every human in the MoGal-verse who sucks it up and just deals with powers they can't fully understand or anticipate.