It makes sense to me, because during swings or snatches you have the relaxation part. So during a set of 5, which takes ~10sec, you still get 4-5sec of rest during the float and/or lockout. With sprints you don't have that, they are 100% go all the time.
Yes I think that's a great point. Alactic energy can be supplied for 10-ish seconds, but not all the muscles are contracting all of the time in swings or snatches. In really hard sprints, you are closer to full-body muscle contraction.