In normal mode, there is a common misconception among tanks about staying outside of the bubble. The thing is, when Mind Crush is happening (and a few seconds after), your position as a tank is wholly irrelevant. He stands in one spot and won't move, and your position as a tank does not affect the black oil placement at all (only the closest non-tank to Deimos does).
As the tank, you can always safely go into the bubble, and you should, to avoid the ticking damage (70% of max health over 10 seconds) you get if you Aegis the Mind Crush instead of going into the bubble. It was quite common to see non-healing tanks (not as common these days) down because of this damage they could have avoided easily.
As for the pizza attack, a well-timed dodge works to solve it, even as the tank, although you do have to take a bit of care to avoid unnecessary movement. And if you want to optimize damage output, you can bring Aegis in an efficient way, but that's completely optional.
And in Challenge Mode, the whole point of it is to adjust your build a bit and bring Aegis, there is really no need to trivialize that.