His job is to do what the player wants. If Nico goes to him and says he wants to stay in Chicago and he wants to sign basically before the season as long as the Cubs meet some sort of minimums for years/annual salary/total money, then that's what the agent does. He can say hey, I think I can get you more if you wait and test out FA, but if that's not what the player wants, that's not what will happen.
I mean, rough estimate is Nico had made around $40M through 2026 before taxes. Pretty good money. But $130M guaranteed is life changing money. Lock that in and you don't have to worry about a down year depressing your value or a major injury. He's not a pitcher so that's less likely, but still happens. We live in a world where we see a lot of people prioritize the most money they can get over everything else. But not everyone does that, and maybe Nico is one of those people.