The player was unhappy and wanted to go, no point keeping an uhappy player no matter what, all that lets put him the the reserves or bench him, never happens. I doubt AW wanted him to leave and maybe was too soft but had we kept him this would have gone on and on and on nad its not healthy for the squad.
If the board had backbone and thought their way was right, they have said he can't go regardless of what wenger said. And given him an ultimatim.