I don't believe a player has to accept a loan move against their will. The conversation regarding loans with players (not just Villa, in general) could be along the lines of 'You can rot in the u23s if you don't agree to the loan to another club', if the player decides to play football as opposed to being excluded from 1st team training and games then the players agrees to go on loan. So ultimately, any manager will be able to say 'It was the players decision'. I am not saying SG was as blunt as this but I think saying it was 'the player's decision' means the player has been told there is no future for them in the 1st team'. Obviously loaning out youth is a different scenario