Idk man.
But Shanks appeared instantly to save Luffy from the sea king and Coby from Akainu.
Either its time manipulation or Shanks has trained with Minato.
Never trust a thread that has "confirmed" in the title as you can be certain that whatever is supposed to be confirmed isn't remotely confirmed.
For starters time manipulation is something quite of a different nature than what Dogtooth did. In the end he didn't even do anything inherently different than what the CoO allows normally, which is able to anticipate on attacks just before they are even launched by the attacker. Dogtooth simply can extend that period for a few seconds. Most likely it's probably not so much that he can actually see the future, but instinctively understands how a scene would unfold in the next couple of seconds.
Secondly Dogtooth himself can already be considered to be highly adept in using CoO, pretty much a master. Shanks being a Yonkou might mean that he's even better at it than Dogtooth, however even for a Yonkou making such a huge leap from a few seconds to a time lord is flat out ridiculous.
Lastly you would think that a guy who apparently can control time would have been able to save Luffy from a 13th rate monster without the loss of an arm...or in fact would have been able to completely avoid that situation altogether and same thing with the War of the Best. I also don't get why you are apparently shocked about Shanks being able to save Coby from Akainu and limit that to either time manipulation or teleportation while a scene like this is quite common in any kind of battle manga. In fact it happened several times in the chapters preceding the chapter where Shanks blocks Akainu's attack as both Ace and Jinbei did the exact same thing, albeit less efficiently.
This chapter confirms absolutely nothing in regards to Shanks, let alone time manipulation.