For those asking 'what was the point in his new contract?', perhaps it's the case that Argyle offered a new one to prevent him walking away for nowt. If he turned it down and another club came in for him, we would have been due compensation as he is under 24.
As it is, he signed - which means he gets to go out on loan and see if he can fulfil the potential the management clearly think he has. If he does well, we can offer him another deal at the end of the season. If he takes it up, great and if he walks away, we still get compensated if he goes somewhere else, as he'll still be under 24.
Unless I'm missing something (which is entirely possible...)