I’m way late to this show, but I’m going to comment in these threads anyway. Really enjoying it so far.
I assume that following the end of this episode, the Kettlemans are going to hire Jimmy as their attorney. If he’s their attorney, then he can’t testify about all the money he saw.
And his phone call just before confronting them said to give him a few hours before coming to get them. Plenty of time to hide the money and for him to get a fat retainer. Then he just has to figure out how to play off Nacho and not share too much of the loot.