Pretty good article. With the speeds that plane runs at, I am kinda surprised it used a trim tab at all. I would have thought it may have gone more towards a servo on the control surface. Sudden loss of trim would for sure ruin your whole day.
Instantaneous accelerations are pretty interesting. Your body can actually sustain quite a few for a very short period of time with no effect. Your brain carries about 3-5 seconds worth of oxygen in it at any given time.
2-3 G's is easy, maybe a little squeezing in your legs to maintain pressure
4-5 G's gets a lot tougher, going with a full g-strain and special breathing, but manageable.
anything more and you need a G-suit, which I do not think any of these guys wear. They just don't need it. I don't think it would have helped this pilot anyway. It sounds like it was such a rapid onset that even with good posture it would have been too much to catch up to with a great g-strain.
I have worked through 6 quite a bit, 7-8 occasionally, and 9 a few times. High G is not fun, and you have to be prepared for it, with no warning all you can do is hang on and try to maintain sight.