Honestly I don't see what you've got such a big issue against Taricus aggressiveness here with, he's super overcrowded suddenly, like someone said, 12 provinces between him and the other guy, that's ridiculously small. Think about it for a bit, this crammed in, where can he go to expand other then an early war? And no one wants that. Settling right next to someone is a pretty dick move. To be honest in my eyes PaPaj is sorta asking for it... Not to mention that he said he'd leave the island... And then didn't? That's also a pretty dick move.
You've compared it to yourself and Gazz, but not only are you guys further away, you both have this natural expansion area, Gazz stays in the south, you stay in your corner of the continent, and then you'll both have plenty of room, average to above average in comparison to everyone else. Unless you're offering your east coast to Storm settlers Tarcius is going to be squeezed tight and your complaints about his complaints seem to be "fuck you got mine"
Of course, that's under the assumption that this game works in the same way as the last one, where getting more territories was typically more cost effective then building up your territories with investments. Since a lot of the mechanical information is missing, maybe that's no longer true. And two people CAN share such a tiny area together and not cripple themselves. We'll have to see, but even so without that information so tightly constricting someone is a pretty evil move.