The idea behind this paid app sounds like a high-school joke. :D

When your mobile turns off, do you "die" with it?

It depends on how close am I to the charger!

Can your disconnection from the online world feel like a form of death?

Permanent disconnection would feel like a form of death (mentally, socially, and financially) but a temporary one can actually feel like enhanced life awareness (unless the disconnection happens at a too inconvenient moment).

And is it really a time when you wish to connect with strangers in the same situation, rather than loved ones?

Nope, of course. Maybe this is where the "social experiment" comes into play.

Cheers! : )