@fapfapfap:
Traveling to the past is a BAD idea, something that creates a lot of problems. However, as Imma said the past is already set so the events leading up to it are already predetermined.
Still it's probably not something you would want to encourage.
The problem with introducing the Time DF into the story is that it'll be used later. Either Toki is alive and she's a giant walking spoiler about the VC or she's dead and someone else has the fruit. I'm betting the latter is the case.
I also don't see the fruit in the present time being used to toss someone into the future again. Kind of like Kinemon's situation it just delayed dealing with Kaido. So maybe the fruit will be used to throw someone into the past. Something that's reckless and ill advised, something Luffy would do.
Encourage what? She was the only one with that ability. No one, much less her royal retainers, is going to force her to send someone back in time even if that was actually possible. Which it isn't. Again, she has no reason to lie to them.
The problem with introducing the Time DF into the story is that it'll be used later. Either Toki is alive and she's a giant walking spoiler about the VC or she's dead and someone else has the fruit. I'm betting the latter is the case.
You're assuming this, but frankly all I expect from Oda is Toki in a flashback related to the VC or something along those lines, due to it being pointed out that she came from the distant past. Or even seeing her previous usages of the DF that led her to meet Oden and finally deciding to settle down. That's really the only "obligation" Oda has to fulfill as far as I'm concerned, not something convoluted in the present day where he gives the DF to a random person and attempts to do a whole other thing with that. Not every DF gets reused in the present day, so I won't be surprised if the Time DF is one of them.
Even if Oda did surprise us and kept her alive, it's nothing new as far as "spoilers" go. We already have a walking spoiler in Rayleigh for example.
The only reason people seem intent on pushing this theory is solely to try and get past Tama's blatant age issue, despite one needing to make a lot of assumptions to seriously argue this theory.