No, not wrong, just designed for a 'ready' motor with fuel already in the bowls. It needs the engine's vacuum to pull the gas from the tank.
During the summer, when I'm riding pretty frequently, I'll leave it in that position. But when it's sat for a while, I'll set the petcock to "PRI," let the bowls fill up & start the bike. During the warm up, I'll switch it to back to "ON" and let the engine's vacuum do the work.
-JP