Again its a story so I'll buy your bullshit as long as its consistent bullshit. Yes we all know the ONLY way to actually go backwards would be to calculate the EXACT point in time and space that you are trying to hit, which frankly would make the flying time machine in BTTF II more believable as it would be easier to give or take a thousand feet in the air than to figure up the exact point to have the tires perfectly meet the road, but again its a story so okay, I'll let that slide.
What I WILL NOT LET SLIDE and what nobody else should either is when their time travel also refuses to fucking acknowledge the power that they have just been given and thus making the time traveler be the biggest dumbass in the universe. I mean in Star Trek generations HOW many times could he have had Sauron without risking anybody AND saving his family? yet he chooses to go back 3 fucking minutes? Or a time ship in Voyager that travels all the way back to the 23rd century from the 29th but the pilot actually says "no time to explain"...WHAT THE FUCK?????
Even Bill and fucking Ted knew that time travel gave you a hell of an advantage but we are supposed to buy that somebody that has the ability to go back in time is too God damned stupid to understand that concept? Really? For the love of God you have ALL OF TIME, from the beginning to the end, so fixing something like his planet exploding? trivial, he has tons of time to warn his race, get his family off the planet, hell they got fricking warp drives and his knowledge of how the next 30 years are supposed to play out, they would be building statues in his honor on Romulus II and that would be the end of it.
With suspension of disbelief there ARE limits, sure I'll believe a world where there are vampires, or where aliens live among us, hell you can spin just about any tale as long as you are consistent in universe. But when you are trying to sell us that 1.- Someone has gone back in time and 2.- he blames somebody for something that hasn't even happened yet and which HE CAN PREVENT thanks to his having knowledge of future events? yeah i gotta throw the red flag and call bullshit on the field, sorry.