He'd already been told of what happened in his own universe, but knowing it happened in more than one... Sentinel may be what he is, but the entire planet dying is a Big Thing. He wonders if whatever version of himself existed on this planet had as big of a hand in the war as he did. It's a depressing thought he pushes away, along with the fact Megatron had gutted him like a fish. Embarrassing.

"Lacking in Decepticons and weak willed to do anything alone, more like." Yeah he'll just settle comfortably into denial. Mmm, comfort zone.