From someone who knows nothing about this stuff, these seem like very simple things to solve given the vast complexity of the rest of the system.
And they also don't seem like massively expensive investments.
> In a tweet from October 2020, Musk wrote "Aspiring to have no flame diverter in Boca, but this could turn out to be a mistake."
Why? What is the aspiration for?
And Elon wants it fast. That means anything that would require tearing down and replacing the launch mount is off the table. So, next up is the water cooled steel wedge. You are right that relative to space explorations budgets, a flame trench and a deluge system are small potatoes. But it feels like they are tangled up in sunk costs and a desire to find the fastest solutions.
a) Pick a cheap quick but possibly insufficient solution, or
b) Pick a reliable solution that costs so much more time that stuff downstream of your project (Artemis 3 in this case) can't use the results of your project anymore
If the quicker fix doesn't, then you are really screwed. You didn't start the slow expensive fix, you have less money, and you may be out of time.