I also found it a little surprising with so much involved that they didn't take the effort to reproduce the failure case, perhaps doing so on a smaller scale than a full vehicle launch if possible.
The problem is that accurately reproducing this failure case is very difficult. You need to replicate the thermal properties of the loading process and the tanks, at the same speed with the same amounts of propellant and helium, effectively meaning that you have to do it with a full-size tank, and with a large amount of pad equipment. This is all extremely dangerous and almost certainly will result, if successful, in the loss of the testing stand.
