The trouble is that you don't really have a conflict then and they can't be antagonists. They aren't fighting against anyone and few people would be actively resisting without some sort of contrivance.
I personally think that the most interesting thing they could have done, and what I'm thinking of doing for a post on Korra ITTL, is make the scary antagonistic political movement be benders who argue that they are being exploited and oppressed by non-bending parasites.
The argument could have gone that they contribute the most to building and running Republic City and therefore they should be entitled the full benefits of that labour. Instead they would point to wealthy non-benders like Sato who live lives of wealth and luxury off the backs of working-class benders. As the show progresses and this movement becomes more powerful the reactionary implications in this worldview, ableism, scapegoating and coded anti-Semitism, would become more apparent as they begin to implement eugenics and ethnic cleansing.
Unlike the IOTL show, where the movement comes across as petty and disconnected from reality, ITTL the movement, whilst categorically in the wrong, would be grounded in the world and the lived experiences of the people living in it and would have some truth to it. Republic City is a capitalist society where social relations are determined by capital and either your ownership over it or the value of your labour. In such a society benders would still face exploitation despite their superior skills just as IOTL skilled labourers are still exploited, in the Marxist sense, by their employers. There is a legitimate grievance but instead of attacking the social system that causes their exploitation their focus is directed at a scapegoat minority and the superficial manifestations of that social system.
That way you could have a nuanced discussion of complicated political ideas where you can disagree with the antagonists but can still understand and even empathise with their point of view instead of the confused mess they came up with IOTL.