It's fine to stop learning at some point. But that's for when you're retired. As long as you still opt to work (and a congressman definitely had the option to retire), you also have to keep up with the world.
What do you mean by "fine". Is it legal or your own choice? Yes. Is it healthy? I highly doubt it. Will it cause harm? I'm almost certain. I think I've read plenty of researchers advocating continued learning as essential, but I can't cite it..