The proper etiquette is to do what you did:

I can see how this irritated you, and one could even say it was inconsiderate of the businessmen. But this is part of travel, and part of optimizing everyone's time. Instead of wasting the receptionist's time waiting until you get there, they could start the check in process earlier by the businessmen hurrying and getting there sooner. Overall, this is more efficient.

Also, look at it from the businessmen's perspective. Elevators are LIFO, assuming you exit the same doors you enter. It was proper for them to get off first.They probably saw a family with two small children who might take awhile to get off the elevator and get to the check in desk. I know that I move much slower when I am with my children. Do they hang around waiting on you, wasting their time and the receptionist's time? Or do they hurry to get to the desk and get at least partially done by the time you get there?

I currently live in Africa. What these guys did was very civil compared to what we experience here on a daily basis! It's life. It's travel. Get over it and move on. Is this really the first time travelling you have experienced something like this?