If Celtic take up the 1 yr option to try and get a transfer fee it would be madness imo.
If its genuinely £1m salary then LG I'm sure would be entitled to expect Celtic to offset any potential loss by moving to Hibs, Aberdeen or any other club who would likely offering nothing like that.
Whatever clubs like us could pay as a transfer fee to Celtic it would never match that compo, if we want him I'd say its what we can directly offer him that will dictate things and if Celtic do offer him the 1 yr then I expect him to be at Celtic for that year, unless we got him on loan in January!