She's a proponent of religious law. That's over the line for me. The entire foundation of the US is secular. As an individual you can believe what you like but the nation and its laws don't take sides.
This is the problem with Islam. It isn't what we call a religion. It includes one in a larger social scheme which uses nasty punishments to force compliance. Sharia has no place in a Western legal model. It's the legal system of Saudi Arabia.
When Sarsour says how nice it is to have interest free loans, she forgets to mention that the reason no one charges interest in a sharia setting is because of the punishments for those who do. This also means financing your future via loans is not feasible because there's no incentive for someone to provide them.
And there's no means to change such things because the rules are divinely defined.
By all means, worship Allah. But don't impose your seventh century legal and economic model on anyone else. Submission. Not.