Imagine the OTA weighing in on the recent net neutrality shitshow. Wouldn't have made the FCC look to smart would it have? That same threat existed for every agency and congress and the executive. Literally everyone wanted them gone.
If anything, a fact checking organisation has incentives to align with or even become a lobby group. We've seen what happens to "fact checking" in the political sphere.
Some would say, if a senator doesn't believe in climate change that's a question of fact, and if they merely received better advice they'd change their opinion.
A cynical person, on the other hand, would say they know full well that climate change is real but they've accepted money to pretend they believe otherwise. In that case, no amount of independent advice will change their minds, as it is not a question of facts but of money.