Yes, we've speculated many times about Rocco being somehow implicated in the Tahoe shooting, and his volunteering to take the suicide mission against Roth as expiation for his guilt. But I don't agree. Rocco looked genuinely startled and upset about the Tahoe shooting, and begged Michael to stay inside. I think Michael sensed Rocco's outrage over the shooting, which may be why he admonished him, in an emphatic way, "Rocco--ALIVE!."

I think Michael selected Rocco for the suicide mission because he believed Rocco was expendible at that point. And anyway, Rocco was Clemenza's choice, Neri was his. And, a subtheme in II is how Neri pushed his way past Rocco, and was trying to push his way past Tom, to become Michael's #2. Rocco may have volunteered for that mission in a last-ditch attempt to regain Michael's favor.