I would not count on getting any miles for a money order. If you have to enter your pin, then it clears through the ATM network and is only a minor charge for the merchant as opposed to the 1.5% charge for VISA/MC. The Post Offfice will only accept the card when used with a pin. The Compubank debit card only gives miles when transactions clear through VISA. I would certainly bet, that Chase only gives miles when the transaction clears through VISA/MC network.

I hope it works for you, but I think your Chase rep was not only rude, but wrong.