Doubt this is in our control. Generally recalling isn't allowed, you'd need a specific clause in the contract and I'm not convinced Rangers would have gone for that given it's not such an attractive proposition to have your plans scuppered mid season
I do find it a bit odd that UEFA Say this is for integrity reasons when a loaned player could clearly have conflicting interests which I'd have thought was a bigger risk. The blanket ban approach makes sense to me.
A Rangers fan I spoke with this morning said they believe he's eligible, if it were to happen. Apparently the Scots don't have a blanket rule against playing against your parent club and so it comes down to the terms of the loan.