re: Workout routine for severely out of shape 50 year old male

Not necessarily. I don't Crossfit, but Crossfit with good coaches can be very effective.

You need someone who is good at teaching skill in compound lifts and someone who designs a real lift progression. Bad coaches will just throw people into squats, deads and cleans. Bad coaches will just throw out WOD's with no progressive overload.

Crossfit can be fine if done right, and the group aspect is a big draw for some people.