Don't solve a problem that doesn't exist.
Usenet access is readily and economically available. There are enough providers that there are sites that review which is best. Google for 'usenet providers' and see for yourself.
The idea of course (at least I think) wasn't to provide generic usenet access on AMPRNet. Instead, it would be used for closed access discussion like this mailing list. Only a couple of hamradio related groups.
Of course this immediately shows the practical problem: the authentication of valid users. You would need to maintain a table of users similar to what the mailing list now has, and when you want a couple of news servers around the world, you would want this access information to be somehow synchronized between them.
Additionally, you may want some groups accessible to "any radio amateur". But then you run into the problem that has been encountered so often: how to authenticate a radio amateur without maintaining yet another user list where new applicants have to be validated by people who would prefer to do more valued work.
Rob