The Big Nothing wrote...
Survival is the most basic instinct. It is the theme of the Mass Effect trilogy, as a matter of fact. Nothing embraces its own slaughter.
Ever heard of a species of creature called lemmings? How about the running of the bulls in Pamplona, where humans seems to embrace the opportunity to get trampled or gored to death? Or the March of the Red Crabs, where they blindly wander across busy roads, to be flattened by all sorts of vehicular and pedestrian traffic? Not to mention whales and dolphins beaching themselves. In many species of octopus, once the female has laid her fertilised eggs, she will just curl up and die. Surely survival instinct should kick in and force her to go on, and brood another clutch of eggs to further propogate the species.
As I mentioned in my first post, no fleet of ships has been recorded of going up to a relay and trying to bombard it, the same way as the Alliance fleet bombarded Sovereign.
The only record we do have, is that an expanding ball of superheated gas and plasma managed to push a relay out of position. From that, you make the assumption that the relays are indestructible.
Heres one analogy that does work. Take Toyotas advertising campaign. Early on, they called their Hilux's unbreakable. Now they have changed it to "virtually unbreakable", mainly due to people going to extremes to see if it was true. By adding "virtually", you are merely stating that conventional means are not enough, and some extreme measures are required in order to break it. It does not mean that it is impossible to do, only very, very difficult.
Besides, you are still taking Sov at his word that the Reapers created the relays. As I asked, do you trust the Batarians about the Leviathon? Neither have any reason to lie, right?