It's not RMT > Normal Character Drgg, it's RMT > RMT. Selling ***on the AH seems to be a rather easy way to make SE lose track of the gil, so it's safer for them than trading character > character or sending 1 mil at a time over the delivery box. You gotta keep in mind, they are a business, even if a poorly ran and morally questionable one. If they get a FCer banned or a any high level character, that's time they have to waste getting a new account at that level or levelling a new one, and therefore money lost.
If you really want to *** them over, flood the AH with randomly priced tonics (or feathers if that's what they use on your server), and if you get lucky, some of that money will come your way. =P
What ever happened to the good old days of just getting it mailed to you, or god forbid just trading the person for it. It's not like it's THAT hard to get around these days.
Seen some Bazaar's where random common drops are set for multiple mil+ gil, and they sell at night for those prices. AH and person to person trade are just some of the options RMT use. Best bet if u get lucky and get an item that an RMT paid for, keep ur mouth shut and be happy.