Originally Posted by
Saiket
I seriously contemplated and attempted this a month or so ago when I noticed those vendors were friendly on the bugged Korean PTR (had worldport enabled). Ran my level one orc into Stormwind and got the same error message you mentioned.
However, there are some things I never had the chance to try. Now that warlocks can summon between maps, it may be possible to summon an enemy directly inside. The only way I can think of is by having a priest in your party mind control him, so that a warlock in the party could summon the priest's "pet" enemy.
It's definitely a stretch, but you never know.