That's silly. If my BTC is in your account being traded and you get arrested, etc. The BTC may still be there, but it's effectively frozen because you have its address and I don't. And unless you've hidden your addresses perfectly - probably impossible to do once they seize your computers, then they can get some or all of it. BTC is great, but it's not magic.
I'm leaning toward dipping my toes in, but statements like this worry me.