I had heard many years ago about the concert incident and I've always believed he did just as was reported, even without knowing about the Johnny Carson item.
We had a talk at one assembly in which the Circuit or District Overseer rather criticized the rumor and those who believed it, saying that the "brothers" had spoken with John Denver about it and he had told them he did it, but it was out of respect for Jehovah's Witnesses, in that he (supposedly) didn't want to "offend their consciences" with his opening song, which was a patriotic song. And supposedly the Witnesses were welcomed back into the audience after this opening song.
I thought this was a little absurd and wondered how the "overseers" could really believe this version. I remember resenting this position a little at the time. But of course they always present other "evidence" to support their stance.
I didn't much care one way or the other. Religion and patriotism cause some of the strongest gut feelings there are - so whatever really happened wouldn't have surprised me. Now if I'd been there, I would have been really mad! So I'm sorry for those who were subjected to this at the concert. I'm quite sure John Denver did what londoner said he did.
I still love his music.
My 2.