You have stated that the "the private key was lost forever due to the glitch". Since this is an established fact according to your scenario, the bitcoin is dead and has been dead from the beginning. Essentially, in "Schrödinger terms" you are suggesting that a dead cat be placed in the box, then waiting for the half-life of the killing trigger, and finally asking if the cat in the box is dead or not. If the killing isn't triggered, it doesn't matter, because the cat was already dead when it was placed in the box. It doesn't come back to life.
To properly pose the question:
A long standing physical bitcoin mint with an impeccable track record has a glitch (unbeknownst to anyone) on their automated assembly line. The glitch results in one out of every trillion coins minted to be missing the private key inside. The nature of the glitch is such that the private key is lost forever. The mint's coins circulate in the market, and everyone perceives that all the coins are worth a bitcoin. Before any particular coin is opened for the world to discover if the private key is corrupted, is the bitcoin dead, alive, or both at the same time?
In this case (until opened) every bitcoin issued by the mint is 0.0000000001% dead and 99.9999999999% alive. Upon opening any coin and inspecting the private key, the wave function collapses and the coin becomes either 100% alive or 100% dead.