SCOTUS is unfortunately more powerful than Congress, at least because they're more capable of doing things.
Luckily they're more aligned with consumer welfare, which is good, as opposed to Khan's hippie "everything big must be bad" standard. This only supports small business owners and VCs, who are probably the most evil people in the US.
I don't think it's correct to paint Khan as following a "big is bad" standard. For instance, in [1] she explicitly says the opposite:
> Antimonopoly does not mean ‘big is bad.' The New Brandeisians—like Justice Brandeis—recognise that certain industries tend naturally towards monopoly. This is especially true of networks. In such cases, the answer is not to break these firms up, but to design a system of public regulation that prevents the executives who manage this monopoly from exploiting their power. A second goal is to ensure that executives face the right incentives to provide the best service possible to everyone who relies on the monopoly to sell or to buy a particular product or service. In the past Americans have used both direct government regulation, and various forms of antimonopoly law and policy, to achieve these ends.
I would believe what she said if she was doing this, but instead she's suing tech companies and asking them to break up in silly ways which is… not that.