That doesn't really pose any difficulties for the rule that you have to refund purchases when you terminate the user's access. Under this rule, Valve would incur a bunch of liabilities to its user base, which it would then mostly not pay because it's bankrupt.

They'd be pretty massive liabilities and would significantly eat into the recovery for other creditors, which could have effects on Valve's ability to issue debt, or might just mean that whenever Valve issues debt there's a clause making that debt senior to any future we-terminated-your-account liabilities.