Helpfile says:

"A more subtle form of multi-charring is switching between your characters with little to no time in between. This is often viewed as scouting the who list in an attempt to see potential pk victims or allies upon login. In order to prevent this it is suggested that you spend between 5 and 10 minutes offline before switching to the other character."

I think it's too short cooldown. I have sometimes limited time to play (have no idea when I'll have to logout), so I'm running around with a lowbie. But I think at least 30 minutes should be the minimal limit, or even 1 hour.

Maybe it's time to update those requirements and make them more strict?