Why? Explain your logic please.
Depends entirely on whether Gus reckons he can get EB to concentrate for the rest of the season if he's not allowed to go.
we sell him now and make as much as we can for him (I'm thinking £750k + clauses will be the maximum we'd receive) .
Yes. No point in keeping an unhappy player who could potentially upset the entire squad and/or even disrupt others who may have glanced elsewhere from time to time (I'm thinking Murray in particular) and bring squad morale down. Also, being clearly unhappy enough to request a move, the player will likely appear unmotivated or disinterested for the remainder of the season, when he would inevitably leave in the summer anyway.