.....Aluminum is not rigid enough. The block will move around a lot internally and will have to be setup really loose on clearances...to run a while if you're lucky. It's not a matter of if it will blow up, it's when. It's difficult to maintain main and rod bearing clearances when even the side bolted main caps start moving and walking around. If it would run long enough. Take the caps off and take a look at them. You'll see signs of abrasion. That's called "cap walk".
Then...to hold that cyl pressure...with a block moving around that much, do you think those floating cyl liners aren't moving around too...and only 4 bolts per cyl on top of that? It's an economical lightweight block.
This is what you wrote.
No one has reached the breaking points of these blocks yet.
You stated that aluminum is not rigid enough for blocks. Well you are just plain wrong.
Don't worry it happens
2016 VW GTI 4 door DSG
1989 Sonic Blue Mustang LX Coupe, 349 ci,
392 rwhp 424 rwtq....Mustang Dyno
"There are three kinds of men. The one that learns by reading. The few who learn by observation. The rest of them have to pee on the electric fence for themselves." -Will Rogers-