First GE supreme clear silicone is known to not properly cure if past the expiration date by even a short time. Also I would not trust it for aquarium usage as many of their tubes actually state that it is not for aquarium use. Some seem to have no issue and swear by the stuff but I have a hunch this was with smaller tanks with less pressure.
Removing the braces, as has been pointed out, was not a good idea. It is like removing a load bearing wall in a house. The stability of the structure is weakened.
No, the tank is probably not a waste as glass is an odd thing. Glass is what is called a amorphous solid which means that it is in a state that carries properties of both liquid and solids. Replace the braces and the probable result will be that the glass straightens itself out to comply to the new structural backing. Glass actually flows. Take a 100 year old pane of glass and measure top and bottom. It will be thicker at the bottom. Sorry, going deeper than needed but stuff like this interest me. Glass, like water, is a really interesting compound if you look into the properties. Water is REALLY off the wall. It is the only known compound that is higher in volume in BOTH solid and gaseous states.
Here is a decent, and mostly plain English, article on what glass actually is.
It's pretty straightforward, isn't it? Glass is obviously a solid. That's what a lot of people probably think after reading this title; but the fact that...
www.scienceabc.com