Oh, Dean's totally upset. He's upset about Sam while doing all this. This is just how his upsetness manifests itself. He's frustrated and cornered and isolated, so yes, yelling at Sam (and Cas, about Sam) is one of the few things he can do. The yelling betrays total concern. The Dean&Cas conversation before leaving for monster gitmo? "HE NEEDS HIS SOUL!" Dean is yelling, and you can hear the desperation and fear in it. And Cas totally notices and gives Dean a Look, and Dean cops to it and takes a second to compose himself. Then Dean lays out the matter practically, with steps - this is what we do, this is what we do next - because they just can't lose this fight, they can't, Dean won't let them lose this fight.

Also, kindness would be wasted on Robosam anyway.

Unfettered by the body, the prayer of a soul is bright but brittle. It sounds like water burbling.