Robinhood is a margin-lending options-trading broker. If a customer falls down on a trade, it is ultimately liable. If a retail customer loses money and makes a FINRA complaint that Robinhood induced them to buy through its gameified interface, it is liable. Risk and compliance likely made this call.
Also, Robinhood makes its revenue from market makers. They are the customers. Clients are not. So when trading these equities gets unprofitable, they will pull the plug. (Though anecdotally, everyone I know on the sell side in equities and equity derivatives is making a killing on this.)
What I can guarantee is nobody shorting GameStop got Robinhood to pull the plug.