All of that however was taken from him when they defeated Dalton. Isn't that more than enough motive for revenge?
Maybe... But the fact remains that the party wasn't really out to stop Dalton. They only got involved because he falsely imprisoned them and stole their property. At the end of the day, he has nobody to blame but himself.
And as I've said, he can't legitimately be angry about losing Zeal AND his crown. It has to be one or the other, since the loss of Zeal was the very thing that enabled him to take power. Even if he mistakenly blames the party for Zeal's fall, it was a GOOD thing for him. (Except for the loss of potential immortality, but he doesn't list that as one of his grievances.)
Okay, so maybe he doesn't see it that way, because he's obviously deranged. But there's also the problem of where to assign the blame. Who was in the party that defeated him? The game doesn't provide a canon answer. It's actually the first time that the game
doesn't force anyone into your party and you have total control over your team composition. Since it could have been anybody, why does Dalton specifically choose Present Guardia as his target? Why not Middle Ages Guardia, or Ioka Village?
I think
Acacia Sgt's idea that Dalton simply blames the entire group as a whole, and calls out Crono as its ringleader despite him not being on the Blackbird, is the best one I've heard. It makes some assumptions about what Dalton could know, but apparently he's omniscient anyway. How else could he even know Guardia exists?
(You can't escape the plot holes, even when you're being generous.)
But there's also the problem of Dalton
literally warning his enemies about his plans. How could those plans even get off the ground if Guardia knew exactly what to watch out for?
Also, we have to take into account that Dalton didn't simply brainwash all of Porre. He simply sparked the flames of war that already existed there somewhere. Porre seized their opportunity and accepted his bid to become the world superpower.
Is there anything in either game that indicates Porre had some kind of pre-existing animosity toward Guardia?