Run ANY act with MP1 and all monsters will be the same level across all acts, so there is no need to farm Act4. The idea behind MP1 is that it doesn't matter what act you farm, you can get the same items.
First of all i'm not really sure that blizzard respect what they say. And they are not stupid, act 4 is way more difficult than any other act, they must have put some interesting stuff out there.
Secondly: another random profile gives you another chance to avoid ban.