One is that most Robinhood users probably under-estimate how quickly they can sell if the price turns around quickly. There might not be enough willing buyers for all of the Robhinhood users who might be looking to get out at the same time.

Another thing is that I'm not a lawyer, but they could be worried that if the SCC finds the discussions on Reddit constitute a conspiracy to manipulate the market, and it's primarily being executed through their platform, and they're aware of the conspiracy and take no action...