Exchanges are able to decide what to halt (obviously since that's what they did). The SEC/class action suits are free to argue the issue, but the likelihood the suit will succeed is low and SEC intervention (beyond an opinion statement) is also low. In the investment space, retail investors are generally treated like children who need to be protected (that's what the SEC is mostly tasked with). RH will make the argument that it was protecting the children from hurting themselves and the SEC will likely go along with it (that's their assumption anyway). Fairness isn't something you generally see in trading.