The Dome ship can be on the lookout for, and intercept, any nuclear weapons about to be deployed on Earth.
In light of this he'd like political leaders freed soon, but they might want to figure out the planned spin on this whole situation first. He would like to talk to Mhalir face-to-face, for that, but expects him to refuse; they're going to need something higher bandwidth than this, though. Matirin's thinking is that the best spin for Earth is probably that there were several Yeerk factions, some of them willing to take unwilling hosts and some working towards willing ones, and the ones favoring unwilling hosts had the upper hand on Earth until the Andalites showed up, at which point the nice Yeerks who'd wanted willing hosts all along were able to negotiate a peace with them. This seems to most neatly account for everything various hosts will have experienced without burning all possibility of Earth governments having normal relations with a Yeerk government, or people on Earth being willing Yeerk hosts later. Though Matirin is going to want to see how traumatized the "voluntary" hosts seem once unYeerked before he commits to being willing to enable that.
He imagines that Yeerks are quite distraught at the losing their hosts and he wants to emphasize that he recognizes he is assuming responsibility for getting surrendered Yeerks who haven't done war crimes sensory access to the universe, somehow, and hopefully not taking a decade about it. He's going to also try to take a not-very-expansive understanding of which Yeerks did war crimes in a culpable way, he knows many of them are less than a year old. He can at minimum have his people morph Yeerk and then force morph-capable animals into various other forms Yeerks can then infest, though his people hate doing this, so he would like something that scales better than that, and is considering his options.