I am not familiar with this product, but I looked over the link provided by Rich (spaniard).
From a quick look, the thing that seemed most concerning is the thing about contact causing skin irritation. This would for sure mean it has to be rinsed thoroughly if it is used in animal enclosures.
I also am confused by the part that says "Acute toxicity Acute oral toxicity (LD50) Estimated to be greater than 5000 mg/kg (rat)" If I'm interpreting that correctly, a rat must eat 5000 mg of the stuff for each 1 kg of the rat's body weight for it to be toxic. That is the same as saying a 1 kg rat must eat 5 kg for it to become toxic. That is crazy. Even water will kill you before you eat 5x your body weight.
But back to the original question, I don't know why this pet store would choose to use this product instead of something more widely used for disinfecting animal enclosures. There is no need to be getting creative since there are plenty of good options available. And when the health of the animals is potentially at risk, why make your own animals the guinea pigs? That attitude, more than the use of this product in particular, would make me concerned about what else that pet store might be doing that I would not agree with.