This is nothing new, Jagex has been doing this for quite awhile now. It seems with the bot nuke and all their latest developments in the "war on bots" that Jagex are slamming the ban hammer down less, and are instead issuing rollbacks and/or wiping accounts that have been involved in goldfarming or buying/selling GP.
Trading 500M a week shouldn't be enough to seriously put you on Jagex's radar or bring any attention to you, but you just never know. Often what happens is that Jagex will bust somebody who is selling large amounts of gold, and then follow the chain of transactions and wipe alot of people who recieved large one-sided trades from that person recently. So its possible that if you trade with somebody who gets busted, that your account could be targeted (although unlikely, so don't panic).
Try to trade and less conspicuous when trading if possible. Do multiple transactions of smaller amounts, or try staking or dicing it over to make it look more "legitimate". You should look around and try to find some guides that are written on how to keep your accounts and cash as safe as possible - I think there is a good one that R2Pleasant was selling that will teach you everything you need to know.