Personally to me I think being able to go back in time causes wayyyy too many issues compared to what it would fix so I feel Oda will just keep it with she can only go forward and this isn’t Oden.
If Oden was alive, this shit would be dramatic as fuck, we all know this.
Recall Jinbe's entrance. He wasn't even dead and his entrance was dramatic with the way he reappeared. He even made fun of himself.
Oden l's reappearance is very nonchalant, which leads me to believe it's not time travel but someone playing tricks, good or bad