[curiosity]

Come to think of it, what you propose is wrong. When a radioactive element decays, it decays into something lighter. Therefore, even if elements lighter than lead are decaying, they cannot possibly decay into lead.

Ergo, even if the universe were infinitely old, it would not be 100% lead.

[conservative_crusader]

Good catch sir. I will grant that the universe would not be 100% lead, however, it does not have to be 100% lead in order for the universe to be incapable of supporting life. Because the universe does support life, we know that the universe must have come into being at some point in time.