If it were up to me I’d consider three things
(1) Was it intentional-ie pulled a fast one hoping no one would notice
(2) Did it make a material difference in the final sequence of play
(3) Did the officials have the ability at the time to intervene but didn’t
If the answer to any or all questions is yes-I would be asking for a replay
1. Impossible to answer but irrelevant, that's why rules are the rules.
2. Indirectly, absolutely but again irrelevant. Rules are the rules and 45 had to be retaken.
3. Yes
The commotion at the end probably worked at like this...
4th official "Ref I've two subs to come on the next break in play" Ref "grand get them off and and on quickly as time is up" 4th official " ones not fully off the pitch yet" ref looks across and see's Manion at the sideline and says "aye I see him there at the side, it's on the blow" 4th Official "think there is another one still to come off" Ref "I'm blowing up anyways, all good"
The ref to be fair would not have noticed that 16 men were actually still involved in the game for that final play, the 4th official probably thought the player went off behind the goals as the sub ran on.
Was the rules broken? Yes, was it on purpose 95% sure it wasn't. Are Glen wrong to appeal? No. And the main question did it actually change the result, did it have any bearing on the game? No
Fine clubs, and move on