Okay this is nuts!!! The shelves ARE NOT too heavy that's ridiculous.
You would never notch anything into the wallboard but you would notch the shelves into the wall tile. You don't need angle iron or aluminum or epoxy or bullet proof glass.
The shelves when notched into the tile will sit/rest on the tile. You can stand on them if you want to. They aren't going anywhere unless you are doing more stupid stuff with the tile adhesive. I don't know where some of you guys come up with some of the nonsense you bring here. You must be being instructed at the local barber shop.
I was told they were to heavy to just mount with the thin set cutting the tile to go around them.
Just plain wrong, that's all that is, just plain wrong.