The wording can be more subtle like "This feed have not seen much activity within the last year" and maybe adding a UI like I did in timeline showing time ago for all feeds

I agree that it good to clean up the Mastodon re-feeds, but it should also be okay for anyone to spin up a twtxt.txt just for syndicating they stuff from blog or what ever.

The "not receiving replies" could partly be fixed by implementing a working webmentions for twtxt.txt