But since you pressed the issue, no the book didn't show us why it needed to happen. The editors and writers told us why in interviews because the book wasn't clear on it. Nor was Logan being so desperate as to come crawling back to Cap properly explained, especially because it made no sense seeing as how his whole modus operandi was killing her, not giving her to the Avengers.
Books tell us that Hope couldn't control the Phoenix prior to her training in Kun Lun, and we see that afterwards she can control can. So even if there is theoretically another way to sucessfully achieve the desired result (and we don't know for a fact that there is), we know that Hope working with the X-Men does in fact achieve them. We know that, because that's the story we got. So again, I'd argue it's less Logan being declawed (an arguement I'll wager the marvel editors and writers DEFINATELY wouldn't agree with you on) and more him doing what needed to be done to achieve the results they all sought. Hope herself would agree with that... and truthfully her opinion is what matters most.
You make it sound as if the Avengers were intending to take her to K'un-L'un and train her from the very start, which is simply false. At the point when Logan turned her over, the Avengers' game plan was to shoot her into space so she could face the Phoenix away from Earth, which would have been even worse than her trying to control it sans water-bucket training.
Wolverine, the guy that always did his own thing and refused to follow orders if he thought he was right, turning over someone he believed was going to destroy the planet Earth to a man that doesn't care about his opinions and pushed him out of a moving plane into the North Pole is a declawing of the character. Although frankly, he started losing his claws way before AvX.
As far as Logan deciding to hand Hope over to Steve rather than flat out kill her (something he could have done while she was sleeping on the plane when they were alone), I consider that less him being de-clawed and more growth on his part. He was willing to give her the benefit of the doubt and try something other than killing her, at least until she lost control to the point where she herself wanted him to stop her.
The Avengers knew nothing. They ran into the situation blind and expected things to work out. They knew nothing about the nature of the Phoenix, they didn't know how hosting the Phoenix worked, and they had absolutely no experience fighting it. You can't honestly tell me they were the right people for the job.
To each his own, I personally find that Logan's "growth" over the last few years have completely destroyed the character. Next thing you know, Thanos will grow to becoming a janitor.