My thoughts are that if everybody is standing up, whether it be top or bottom of the stand, it is impossible to say for certain how many seats are vacant. You can see folk standing in the stairs right enough, creating a health and safety issue. But if turnstile records show that there were 200 empty spaces then that is more likely to be an accurate figure than some random guesswork.
My interpretation of what Caldwell actually did or did not say.
He did not say that the number of Celtic fans meant they could do as they pleased. He did say that the Police and Security team, faced with a situation, decided that clearing the congestion and returning folk to their correct seats was not a practical option given the numbers involved and taking into account safety issues. If the Police were prepared to accept that non action, are we really saying the Club should have overruled them? I assume the Police Match Commander has the final say? If the Club had gone against that instruction, I wonder who would have been liable for any resulting injuries.
Caldwell did accept that there was an issue with fans electing to go bottom tier despite having upper tier tickets. That is an issue that must be addressed by him and the Club and should have been thought about ahead of this game. Had it been, we would not be having this conversation. But it clearly wasn't. He also said that First Aiders were able to access the stairs so that aspect was covered.
At the end of the day, I believe the Police made the call and it was the correct one given the situation they and the stewards were faced with. Unlike last time there was no evidence of exit doors being forced open or stewards/police assaulted to allow non ticket holders access. But lessons need to be learned and the Club Security team, aided by the Police, must have a system in place to ensure visiting fans can only access the area for which they hold a valid ticket.
Tynecastle has a similar issue regards upper and lower tier ticketing but from what I witnessed when we visited last season, their stewards/police intervened before overcrowding became an issue. Nobody was allowed to stand on the stairs either. Although that meant Motherwell fans with upper tier tickets had to move elsewhere, under protest. Easier to do though with a few hundred compared to several thousand.
I think we should be relieved no injuries resulted but at the same time look to the Club to ensure the ticketing situation is not repeated. However it is impossible to stop 4000 or so fans from standing up if they want to. I also think the Police and League Authorities will have the same outlook.