...what did he want to say about this all? What could he?

Hmm...

Finally, "Take good care of the kids." He knows she would, that it didn't need to be said, but... still wanting to. Kind of like what he thought his last words to Trunks had been, to look after Bulma. He had known the boy would, as much of a brat he was. And he knows if anything threatened their kids that Bulma would move worlds to make the threat suffer for even considering it.