A reasonable hypothesis. Since there is no evidence that domestic cash-only and foreign cash-only buyers have different bidding patterns, we can then conclude (contingent on your latest hypothesis) that the link with the stats does not support the idea that it's mostly foreign buyers bidding up the price.
It's not a hypothesis - it's part of auction theory for markets that use absolute and reserve auctions. Why are you so adamant in attempting to redefine this to dismiss it?
