Put another way, just because they have to halt buying, they don’t owe it to their customers who are holding to not allow other customers who want to sell to do so.
I think that shitstorm is preferable to allowing brokers to manipulate asset prices to protect themselves.
I don't think that "biting off the nose to spite the face" is the approach I would prefer when it comes to my money. And, I think, a lot of people would agree with me this.
Also, the whole "protect themselves" line sounds like pure outrage without thinking about the actual consequences. If your brokerage doesn't "protect itself" and implodes, what do you think is gonna happen to the value of your assets sitting in that brokerage (as well as the assets of everyone else in that brokerage)?
The idea that a broker going under wipes out all its members assets is just not true. MAYBE some stuff in flight would have issues. All the capital requirements and regulations are designed specifically so the brokerage fails first before customer assets are at risk. And again, still SIPC insured.