Those agencies I'm referring to make up over 80% of all government employees, so the entire government practically has a bad setup and implementation (which I would not argue with). I see no reason why you cannot use a password manager myself, but I'm not writing the policies. You didn't quote any guidelines as far as I can tell, you just named a couple of agencies. The closest I can find to any agency using a password manager is KeePass at GSA, but I can't tell if that's for use on government machines. If you're familiar with Zero Trust environments, and you've seen NIST 800-207, there is an entry from November 10th, 2022 (just 33 days ago) which is one of the first times I've ever seen password managers brought up. And this doesn't necessarily refer to government furnished equipment.
I'd refer to my own internal cyber security but raising questions about this may put me in the hot seat.