The article says why. The US Chamber of Commerce has fought tooth and nail against climate legislation because they view themselves as "job creators" and see anything that threatens corporate profits as an existential threat to society.
They've only recently been forced to admit that climate change even exists, but it's still like pulling teeth because they insist that any solutions have to be technology driven from the private sector, with no mandates whatsoever from government.
Nuclear energy is probably our best bet for big scale carbon-free energy. Renewables without (costly, often impractical) enormous storage can't do the job, and keeping gas plants for peak loads isn't helping. Nuclear has enormous upfront costs, making it a somewhat risky investment, so big subsidies are required to get it up and running. After that you get carbon-free electricity for decades.
“provide payments to prop up carbon-free nuclear energy”
I would be also against a bill that includes this.