Dick, don't get so defensive. Gibb is not telling anyone how to sing anything. We all, including Gibb, fully accept that the genre of chanty is now almost exclusively entertainment and therefore fully open to interpretation. However, the rider to that is if we pay no attention to how the songs were originally used then perhaps we shouldn't call them chanties. We have plenty of replica chanties in our repertoire but that's exactly what they are, imitations and that's how we present them.
FWIW and now my opinion. Shenandoah is a beautiful tune however you use it and whatever metre you use. I often play it on my concertina just for that very reason, but make no attempt at any authenticity. However when I sing in the Hull Chanty Crew I like to think we keep as close to 'authentic' as is possible, which is why I try to dissuade anyone from singing Shallow Brown as that god-awful dirge! (IMHO)