I'll actually lean towards ETD's side if we are talking strictly SealFit and not just CrossFit. Most of their workouts tend to be at least an hour long if not more, and that's without the warm-up.
So let's just say it takes you 15 minutes to get to your gym/box, another 5 to change, 10 minute warm-up, 1 hr workout, 5 minute cool down, 5 minute shower, 5 minute change, 15 minutes home/back to work. You are talking about 2 full hours.
That's tough for anyone to do, regardless of the schedule they keep.
Sealfit is pretty hardcore so if you are doing it then you know the time commitment and physical commitment and it won't matter if you are a shift worker or not.