This is robinhood's fault. He's not wrong that instant (or same day) settlement would be better than T+2, but there were plenty of other brokers that did not restrict trading. This was a liquidity issue for robinhood. This is a risk you run being a "cool startup that moves fast and breaks things" in the arena of securities trading. Additionally, Some of the bugs they've experienced are absurd in the context of a brok…
It seems they raised deposit requirements potentially more than was standard. This needs to be investigated.
WeBull's CEO claimed their clearinghouse told them to stop selling these securities (no mention of deposit requirements). If they really weren't even given an option to deposit more, that seems to me to be an abuse of power by the clearinghouse.
Finally, was the DTCC not having the long side cover the risk on the short side? It seems to me, the vast majority of the risk was on the shorts. The short side seemed to be made up of mostly large hedge funds, so if one went down, it would have been extremely difficult for the DTCC to front the cash on all of their trades, and of course shorting has infinite risk. The long side was finite, was distributed among multiple brokers and then even more distributed among retail investors. It seems like the risk was low there.