On an off-topic note and addressing people that also play TF2, are the people against the single-player ban the same people who are against Valve's actions against idlers in TF2? Seems like gamers are constantly jumping between supporting these third party programs violating ToS and then getting punished and going against it.
OT: I wonder why you couldn't have used the implemented cheats that Blizzard puts in for you to use, or use the Map editor if that does not suffice. I don't see how it wouldn't, since most Trainers consist of "Unlimited Minerals, Unlimited Vespene Gas, etc", which is what the in-game cheats already cover. Again, from my experience, Trainers do not distinguish between single-player or multiplayer, therefore, you can use it wherever (Albeit with difficulty), even in multiplayer.