What valid reason is there to ban scan tools? Seeing none, it sounds like the auto auction is complicit in the scam. Because if you cannot inspect a vehicle properly before purchase and are rushed into purchasing what is probably a lemon, then it's definitely a scam. And how convenient it is that they have their own "condition" reports. Hello CarFax, my mechanic, and a scan tool or no sale.
>>sacnor+(OP)
Perhaps to avoid a fake/tampered scanners creating a he-said-she-said situation. Independent inspection is probably a good middle ground if trust is low and expected sale price justifies the expense.