Its the same depending on how you word it. You are hacking an ATT phone to run on TmobileYou'd be comparing apples to apples (pardon the pun) if you were hacking iphone software to run on a motorola phone. But you aren't.
You guys can keep trying to twist it around but its no different than hacking the iphone. Both are violating the eula, both are modifying an OS, and apple is possibly "losing" money with both since they get money from ATT contracts and they get money from mac sales. If you think both are wrong then fine, but try not to have double standards.