I'm in full agreement with your demonstration, however, as to the case at hand, it appears to me that it's not really the point : the fact is that it should not be qualified as a "presale" and Paypal here is not a trade intermediary but a postman. If that's not the case, Paypal needs to explain how "crowdfunding", which depending on the viewpoint could be characterized either as a capital investment or as a donation and therefore in any case NOT a commercial transaction, intersects "presale" which definitely is a commercial transaction...