Personally, I view hundreds of predominantly single-occupant, predominantly internal-combustion automobiles clogging up my neighborhood's main thoroughfare 18 hours a day to be a jerk move at a scale much more vast than inconveniencing those motorists for some number of minutes. The goal of their transit is irrelevant, as you say.
But anyway. This frustration is why "share the road!" is stupid and inconveniences everyone. I don't like it either. As an occasional bicycle user I don't want to be in your lane any more than you want me to. It's very dangerous and 1/10 motorists are needlessly belligerent. Perhaps you should contact your local transit authority to support the addition of a separated bicycle lane for that main road, so that you don't have to share a single lane with cyclists. Or the side roads you speak of should be beefed up as bicycle infrastructure and cyclists banned from the main road. I am quite sure that there is a reason they're on that main road, because I bet it is unpleasant to cycle on it.
If you don't like sitting in traffic, (who does?) you have to think like a bicycle user, and reduce blockers to cycling because if your area has population growth and finite land, there is no solution to traffic other than getting people out of cars and into other modes of transport, including bicycles. Blaming bicycle users for cycling and saying "why don't they cycle somewhere else?" is not a valid solution.
I refer you to my previous comments explaining how I also don't like "share the road" idea. We are on the same page on this. Go complain to your county or city or whichever rather than wishing literal death to your neighbors.
Riding on a main road and slowing down hundreds of people by orders of magnitude is an jerk move.