The problem with this analysis is that Robinhood didn't choose to block buy orders, they were forced to because they were no longer able to fulfill them. You can argue about whether Robinhood should've been better prepared for the volatility that arose (and that could be an interesting conversation by itself), but they weren't. GP claims "they shouldn't have done it", but continuing wasn't an option. The only other choice they had was to suspend trading in GME all together (both buy and sell orders), but I don't see how that wasn't strictly worse for them and their clients.