I've never heard of Valve removing single games from an account before. It's common knowledge though that if you ever do a charge back for a purchased game they shut down your account and it becomes irrecoverable.

It's a blanket policy and a reason why I never use Paypal for Steam, use a real or "throw-away" credit card for Steam purchases. Alternatively, you could not buy from Steam at all, I don't anymore but it's too late for me. I already have over 200 games with them and worry about losing access to everything.