Snapped a little on the high side for a bearing seizure - but, could have. Most of mine have snapped closer to the crank from bearing seizure. Fortunately, I haven't blown up a Honda or anything else for that matter for a long time. If not a bearing seizure, then mine usually let go right below the wrist pin - makes for nice mess.
Did the bearing seize or not? If it was detonation, I'd say it was massive turbo type detonation with lots of boost.
I'm thinking bad rod and it flat let go.
That's nasty man - salvage flywheel and toss bottom end - maybe salvage head. Wait, he did say it went out the oil plan. I can't imagine the block surviving wtih as much rod as was left on the crank - unless it let go at the cap and flew off downwardly and kept on going.