Not being able to cover your obligations with current cash flow (the situation where they would be defaulting on their obligations for existing trades they submitted) is pretty much the definition of bankruptcy, isn’t it?
Knowing this in advance and preparing for it is exactly the business RH is in, and they should have been much better prepared for it.
If they were unable to meet this requirement it is a clear default on their obligations as a broker, and they would be bankrupt at this point.
It would be like if I was trading on margin, but had no idea what my margin collateral requirements were - one day prices drop on the stock I’ve been trading and my broker does a margin call, and I’m going ‘uh what do you mean?!?’ when they liquidate my holdings because I never paid attention to any of that paperwork they sent over. Is it my brokers fault then?