Still seems a bit farfetched, not to mention that I highly doubt Gaspar has that amount of power. If he really could do amazing things like manipulating Gates, why couldn't he just do something to Lavos to stop him from destroying Zeal in the first place? The guy can create a Chrono Trigger after years of hard effort, yes, but I highly doubt he can manipulate the flow of time itself...even if he is the Guru of Time.
Also, the Gate at the Tyranno Lair was not "newly made", it was created over 60 million years ago from Gaspar's point of view... >.>
I also don't see why he wouldn't just say "Oh yeah, I'm the Guru of Time, I can do stuff like that," if he's willing to put enough faith in the Chrono team to defeat the godly parasite that is eating the world from within. Not to mention that he actually does admit that he's the Guru of Time.
Also, Occam's Razor doesn't agree with it.