I would suggest not starting a logline with the word "he's". A logline is meant to tell me who the protagonist is and this normally happens first thing where you have used the word he's instead. None of the logline tells me who the protagonist is. It also assumes we have outside knowledge by assuming we know why this man left the 21st century and how. This is information the logline should tell us if it is key to the story. You will know best.