Regulators are (intentionally) designed to be able to exert pressure with a lot of discretion. The financial industry is having a ferocious rage fit. The NASDAQ CEO even went on air calling for immediate SEC regulation... the irony didn't even seem lost to him.
Getting on the industry and SEC's bad side is the liability, and that kind of pressure is a big part of hw the SEC actually "regulates." It isn't strictly through rules.
Platforms are there to enable interface with market, not decide what I can and cannot buy from that markets.
If Citizens United says money is speech, the financial system effectively has no guard rails
Except when it does for the institutions
Citizens United says specifically that when a bunch of people take their money and get together and start a new corporation (Citizens United) (a not-for-profit corporation in this case, though not a charity) and the corporation proceeds to engage in political speech (by filming a movie named Hillary: The Movie)...
then the corporation, as an entity, is considered to have the rights like the right to free speech, because it is owned by people who have rights, and this is a way for those people to exercise those rights together. Therefore this political speech is protected by the First Amendment, and restrictions on it are evaluated on the standard of strict scrutiny, and the FEC cannot halt this distribution just because the corporation was using money to make it happen.
(You will notice that people are not allowed to band together and exercise the right to vote, and thus corporations don't get to vote.)
This concern is relevant to GME, BB, AMC, etc. because folks are joining Robinhood, Webull, and similar apps in record numbers in a rush to jump in on these hyped-up opportunity.
https://www.bloomberg.com/opinion/articles/2021-01-28/robinh...
Go look at past instances of Robinhood going down and the amount of people who claim they're going to take action because of lost money