The only absolute I mentioned was that holding threat should take priority over DPS.
With that in mind, I'm not saying that tanks should constantly spam flash. This is an absolute you jumped to by clipping 1 phase out of a larger hypothetical scenario used to argue a point about new tank expectations.
I am arguing that it is silly to say something like "the tank should be able to hold threat on 1 of the 2 targets". If you're going to allow 1 loss in a standard, there's no reason to not allow 2 losses. If you're going to require 1 be held, there's no reason to not require that both be held.