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While it is true that other failures occurred before A2001 on floor 13, ...
In the context of the Hulsey draft report, which is the context, the topic currently, this is all the facts we need.
It is clear, and you acknowledge, that, in the NIST simulation, WTC7 had suffered multiple structural failures from the fires by the time A2001 on floor 13 started to fall.
Once we have this down, any analysis of A2001 and C79 that does not take into account the state of the surroundings (other girders framing into C79, floor slabs all around, situation on adjacent floors) is necessarily incomplete and invalid.
I think NIST's approach can be criticized, even doubted. They apply all the connection failures from ANSYS at the same moment - that's unrealistic, of course. Failures occurred over the course of quite some time. Ideally, each time a total vertical connection failure occurred, they should have stopped the ANSYS simulation, imported the entire ANSYS situation into LS-DYNA, let LS-DYNA run its course until all motion arrests, then import the resulting LS-DYNA situation back to ANSYS.
Better yet, return to the fire modelling with the LS-DYNA result, etc
Loop and repeat this circle with every new vertical failure observed in ANSYS, until either global collapse has occurred, or all fires are out and steel is cool.
Obviously, such mutual feedback looping between the various modelling devices would have been exceedingly complex, and most likely computationally infeasible (and far too expensive).
So NIST settled on a somewhat simplified strategy - let damage accrue in ANSYS until enough has accumulated to result in LS-DYNA collapse progression.
This is then NOT (exactly) what happened in reality, but perhaps a "good-enough" approximation.
In that view, as was as in reality, the collapse was not the result of one and only one connection failure, but of a multitude of accrued failures. Perhaps (in hindsight, with a view to accommodating Truthers) it was not smart by NIST to pick out one failure as THE one.
The Truth Movement for a long time has put blinders on and focused solely on a single connection - and implicitly assumed all the rest of the structure to be pristine.
Hulsey has followed that pattern. It's one of the reasons why his report FAILS completely all its purported objectives.