I'm pretty much with you on most of that. The one thing I can't ignore is that it looks so incredibly similar to the found Mary Rose bows (and the Viking Bow). The cross section is identical, the dimensions are identical, the length is very close if a tiny bit short.
I really like the idea of Otzi trekking across the alps to trade, it works logically and there's no reason for it not to be so. However, if you were going to trade a premium stave of yew, surely you wouldn't reduce it to dimensions which we as bowyers know make an excellent, high performance bow first. I know that most bowyers on here and other forums wouldn't bother paying for somebody's half finished bow. For a stave, yes. With the options available to layout your own personal design, choose your draw weight, fit the length to the user, but not a half finished bow. It's not worth anything to anybody other than original craftsman.
Looking at the cat scans, the bow cross section is complete. It's been rounded nicely, the edges of the back are smoothed (usually only done right at the end of work, before final tillering) and the thickness and profile tapers are cut and finished. The only thing that would suggest that it's not a finished bow are the mystery of the string nocks, and the tool marks. I find it really believable that in the absence (or lack of knowledge) of something like sandpaper, a bow would look rough to those who use abrasives to finish. The nocks... who knows. But again, he was found with string. You gotta admit, a body found with coiled bowstring, finished arrows.... and a bow.... sounds like a complete picture. To take the bow (which looks finished apart from the tool marks) and theorise that it's just a blank doesn't work - to me!
It's like the people who think the Mary Rose went sailing straight into battle with crates of unfinished bows. It's ludicrous, and doesn't work, logically.
I'm no expert, not by a long shot, so all I can do is theorise and put forward my personal opinion and hopefully you won't see this as an argument, but as a set of opinions as that's all it is. Otzi fascinates me, and I wish like you there was just that missing piece of the puzzle that would answer the questions, but we haven't got it, so we'll have to sit back and just... guess!
Interesting thread though! Original topic disappeared somewhere, so hopefully Kevin won the argument...