Also, it was so odd of Emma to have no problem with taking Past Marian back to the future and yet she told Rumple to drink the memory potion to forget about saving Neal. What? Emma didn’t want to alter the past but she brought back Marian? That makes no sense either.
Emma did leave Marian on the ground after inflicting a life-threatening head injury, so I’d say at least Emma’s subconscious knew not to mess with history.