"Those people are just looking for a reason not to get exercise, and are better off dying around their mid 50s."

It's a ridiculous statement. Life expectancy, even among those who do not regularly exercise, is greater than 50. My mom is 70, and the most exercise she's ever gotten was from walking (and not for fitness, just around the block, or meandering through the mall). She certainly would not have been better off dying in her 50s.