It is an interesting debate surrounding young Jack Walker that's for sure.
On the surface it sounds like our very own Curtis Naughton. The only difference being that Walker hasn't demanded the 1 shirt or even to be the starting FB. Naughton wanted to be the number 1 ahead of Brett Kearney. However same result, Naughton left and so will Walker.
I do think his agent will have turned his head a little, however the player also has a right to say how he wants to play. If he sees himself as a fullback and wants that specialist fullback training then I can't see why Leeds wouldn't do their best and provide that for him. Has he played anywhere but Fullback so far for the first team? If so then surely Leeds see him as a fullback too which makes their decision more puzzling.
I can't comment for everybody but players sometimes enjoy their role. Me, for example, will play anywhere. However if I get asked to play halfback I will likely say I'll do it but it wouldn't be best for the team as I am dog dirt, I am however a good hooker. So changing my position would weaken the team, maybe that's Walker's way of thinking. Who knows.
In reality, we can all speculate but non of us really know what's going on in his head to leave, and we probably won't know 100% of the details. I hope he does stay and become your fullback for years to come though as I am a huge fan of academy products playing first team rugby with their parent club.