Them saying that is like me saying Bizmuth isn't radioactive because it's half-life is many, many times longer than even the most conservative estimates for the heat-death of the universe.

In finite time that's effectively true, because the universe itself would decay before a block of bizmuth lost any significant weight - but it isn't physically true, because with infinite time a block of bizmuth left completely alone would evaporate away via alpha decay.

And that's the point of infinite time - to let you throw away time and probabilities as obstacles and strictly focus on whether something could physically happen, rather than the odds of it occurring.