As far as any interests Snap On retained in the tools - it would depend on the financing agreement and if they had filed a UCC financing lien at the time of sale.
Technically - unlike a vehicle with a VIN or equipment with a serial # - it could be problematic to positively identity any hand tools sold under a financing agreement. Perhaps they do have a unique numbering system - I am not a Snap On user. If he defaulted, the financing agent (maybe a web bank) would try to recover from him. If the tools were disposed of or sold - the seller could be investigated for defrauding a secured creditor. I doubt if anything could be done to a buyer of tools without an identification #. That said - I doubt it would be pursued. I don't know if Snap On carries its own accounts or uses a third party.
Ignoring the ethics of purchasing tools you know are financed and not paid for; I believe you are correct. Scanners and boxes are serialized so can legally be proven to be the same tool. Most hand tools do not.
I don't like the weekly financing model and I think it often puts techs in precarious financial positions and certainly borders on predatory. I have sympathy for the dealers as well. They are often deeply in hock and a few customers skipping town with an unpaid balance could tip them into bankruptcy.