I don't think your take stands up to very much scrutiny at all.
If this is about people trading on RH on margin, then just... stop allowing people to use margin to trade GME etc. "If you wanna buy GME you gotta have the cash in your account to cover it".
Problem solved and you don't need to prevent people from buying a stock they want to buy.
RH users are the product, not the customer. Why in the world would you expect RH to act in the interest of their users over the people that actually pay them, e.g. market makers like Citadel?
If this is about people trading on RH on margin, then just... stop allowing people to use margin to trade GME etc. "If you wanna buy GME you gotta have the cash in your account to cover it".
Problem solved and you don't need to prevent people from buying a stock they want to buy.
RH users are the product, not the customer. Why in the world would you expect RH to act in the interest of their users over the people that actually pay them, e.g. market makers like Citadel?