Well put, Matthew.
It is indeed quite possible/plausible that Phil Saumarez reworked an earlier song. His song is only the earliest extant version, which certainly doesn't exclude earlier versions.
However, in my experiencen in the use of later ship names in versions the actual ships mentioned (and we can presume they actually refer to contemporary vessels) need not have been involved in anything like a similar skirmish. Their name has been included in a new version simply because that vessel has been in the public consciousness recently and any audience can relate to it more readily. This is one of the ploys used by the hacks who rewrote these songs for sale on penny sheets in the streets. Of course this alteration could also happen for other reasons. Jim Bloggs decided to alter his version to 'The Lion' because his brother had just come home from serving on her, full of stories of daring exploits. What we have in the numerous related songs in this case is the constant interaction between print and oral tradition. The only problem this presents to wouldbe researchers and historians is they often overlook the print side of the matter.
BTW I don't find any of your, or any other researcher's, efforts daft at all. It's all about increasing knowledge. I frequently have disagreements with other researchers on this forum, but it all contributes to the increasing wealth of knowledge. The biggest blows to that are when wonderfully knowledgeable people like Malcolm and Bruce pop their clogs.