Except the death at the Manchester Derby was totally avoidable. The coroner was even moved to write a report to both United and the local authority to prevent future deaths.
The man fell down steps when exiting the ground allegedly because he couldn't reach a handrail because stewards where standing in the way. On this basis it has no relevance to the debate. As I say, could have happened any time and anywhere and irrespective of safe standing or not.
You are basing your analysis on one aspect of the green guide evacuation. You also have to consider the guidance regarding exits. The green guide sets clear standards regarding the size of exits and also the minimum requirements for barriers along those exit routes. Instead of being fixated on evacuation times you also need to consider what happens when stairwells and exit routes become overwhelmed. For every Bradford fire there are far more Ibrox disasters.
You made a point that the number of stewards needs to increase if the crowd stands. This is not the case. The number of stewards relates to the number of people in the stand (and their training etc) and does not relate to width or number of exits or the speed at which people move to exit.
As far as I can recall, the deaths at the Bradford fire were related to the inadequacy of the escape provision (with some final escapes locked), the speed of the fire and the inherent risk of fire arising from accumulation of rubbish under the stand. As I recall, the fire was at least for the most part in a seated section. 66 people died at Ibrox as a result of people turning back on very steep exit steps (actually outside of the terraces). I can't see any relevance to this debate as either event could have happened standing or sitting
Standing isn't being stopped but you seem to be ignoring the fact that we are unable to control what is happening and instead want to introduce more people to the same amount of space.
Again, you made an argument that more stewards were required for standing because there was more risk in a standing area as people exited quicker than sitting on a 1:1 basis. Actually, there is marginally less risk as the time to evacuate is less (and the number of stewards does not change). Rather than a fixation, the evacuation time is a major consideration in calculating the safe capacity of the stand and that calculation includes consideration of number and width of exists as well as smooth flow (barriers, constrictions, reservoir areas and the like).
I think you are confusing the idea that more stewards are required if there are more people (which is correct) with the idea that standing requires more stewards on a 1:1 basis, which it does not. Either that or you're being deliberately obtuse.
What I am not ignoring is, is the fact that standing in a seated area - even on a 1:1 basis, is unsafe. If it can't be controlled then making sure that everyone stands behind a barrier can only make it safer. Providing those barriers would be the price of making standing safer. Not an increase in stewards because they wouldn't be needed.
I have never denied that going on to increase capacity beyond 1:1 would require both more or wider exits (and more stewards) - hence the 1.8:1 ratio - but I suggest that would be the price of greater availability but not at the expense of safety.