If that's the case, then you are very likely right. It would make sense - from those "facts" - that they were attempting to climb the regular route on Mt Hood, and it sounds as though they planned to climb quickly. Therefore ... not a huge amount of gear in their packs. Probably they did not carry shovels because they expected to return before the storm, and probably no locator beacons because they never expected any serious difficulties on the way.

It's possible they got off route during the ascent - and went off in a wrong direction. That might have put them in difficult terrain and caused an accident. Hence, one climber stayed with the injured team member and the other one descended to seek help. Unfortunately, the climber descending quickly was subsequently killed - possibly because he moved down into difficult and hazardous terrain.

This is all very speculative.

other Pete