That - genuinely hurts. They were trying. Well, at least he was trying, and he had a substantial faction very loyal to him. Mhalir was never the leader of the Yeerks, and, well, he had quite a lot of influence but not infinite influence. There were some who from the start didn't care about consensual hosts. Mhalir fought back hard, and - damn it, he would have won that round if not for the surprise attack. Which was a surprise, even if there had been some warning mutters, before, it escalated so quickly and it was the first war in his species' history and how...was he supposed to know...
But it doesn't matter in the end whose fault it was, or how unfair. Or how much he misses Seerow and wanted him to be proud. This is the reality they have now. One where the Andalites tried to pre-emptively take out everything the Yeerks had built so that they could grow, and Mhalir wouldn't have made the choice to start that war, he never wanted a war, but he wasn't going to just give up. And once you're in a war anyway, the thing to be done is win it, and figure out terms from there.
Except that the Andalites have a weapon to destroy Earth, and might be scared enough to do that...
<You are being very reasonable in doubting me> he says to Leareth. <I cannot ask you to do otherwise; I am the one who must prove things to you, here. But - start with the premise that I am telling the truth, and I - we are so alike, I never thought to...> Focus. <If you were in my position, and wanted this to go well and not disastrously, what would you do>