I'm not going to pretend like I'm sat here on my couch and know more than those scientists, so can someone help me understand how they generated a free will hyp

I'm not going to pretend like I'm sat here on my couch and know more than those scientists, so can someone help me understand how they generated a free will hypothesis about this? Seems to me I could explain this with something like "short term memory assignment is delayed," i.e. the decision was made by the conscious brain, but the memory of making the decision had a long write time and therefore a later "timestamp."