Passenger

oh I get it. Starscream said that to reach prehistoric earth he had to fly past all space and time. Obviously that means that he could have crossed dimensions at one point in time but did'nt so Waspinator took advantge of his spark being rendered invincble by Starscream possessing him and actually tried to cross dimensions and made to the TFA universe where he entered Tutorbot's body but was unable to take him over, however his indestructable spark had a similar effect on Tutorbot's body and thus allowed Tutorbot to survive all the tinkering and damage he recieved in TFA