Tell your friend he needs to learn the rules of the game.
Also, if this was a courtroom, the judge would probably say the burden of proof was on him, not you. So he doesn't want to accept this thread as proof that you are right, fine, but it should be pointed out that he has absolutely no proof that you are wrong, either. The card by itself doesn't provide any evidence that you are wrong - so that means means its up to him to prove that you are breaking the rules. Fact of the matter is he won't be because there is NOTHING in the rules anywhere that says you can't morph a creature on the same turn you play it, nor is there any rule about not being able to turn the creature back over and keep flipping.
If he stilll doesn't buy it, you should ask him why he thinks Wizards designed the card in the first place. What would be the point of the card if you couldn't keep flipping it back and forth? Even without stuff like aven farseer, clearly the card is designed to be a cheap wall that can becomes a 2/2 and attack if you need it to, and then switch back to a wall if you need defense again.
In the future, you can resolve rules issues by calling Wizard's Customer Support line, (Not enough people know about this option, actually). You can get an official judge on the phone and they'll answer your questions right quick!
