I was thinking about what I wrote in my previous blog about Bava Metzia page 48, and I realized that I really have only one answer there for the Rambam. That is the idea of the Baal Hameeor and the Ramban that the decree that pulling acquires is only for the seller and buyer. The Sages would not have made a decree for a gentile. Therefore, when the Jew pays with money of hekdesh (the Temple) to a gentile (without picking up the bought object) he transgresses meila because the gentile has acquired the money regardless if the Jew has acquired the bought object or not. You do not need the idea of the Maharam of Lublin that the decree of the sages was only that the buyer does not acquire until he picked up the bought object, but that that the seller does not acquire the money. I think that idea does not solve the Rambam in any case, because if it would be so, then what about the case when the Jew buys from another Jew? There the law is that he does not transgress meila unless he picks up the object. But if the seller acquires the money, then the buyer should transgress meila even if he has not acquired.--------------------------------------I was thinking about what I wrote in my previous blog about בבא מציעא דף מ'', and I realized that I really have only one answer there for the רמב''ם. That is the idea of the בעל המאור and the רמב''ן that the decree that משיכה acquires is only for the seller and buyer. The Sages would not have made a decree for a gentile. Therefore, when the Jew pays with money of הקדש (the Temple) to a gentile (without picking up the bought object) he transgresses מעילה because the gentile has acquired the money regardless if the Jew has acquired the bought object or not. You do not need the idea of the מהר''ם מלובלין that the decree of the sages was only that the buyer does not acquire until he picked up the bought object, but that that the seller does not acquire the money. I think that idea does not solve the רמב''ם in any case, because if it would be so, then what about the case when the Jew buys from another Jew? There the law is that he does not transgress מעילה unless he picks up the object. But if the seller acquires the money, then the buyer should transgress מעילה even if he has not acquired.