I dont care what the hazards are. I dont even care if they have had geo trackers cut them off every day they have driven.
That depends. Was the semi keeping a safe following distance between him and the next vehicle, and you just cut in front of him, thereby diminishing his following distance? If that's the case, then you are the one who put yourself at risk by invading his safe following distance he had already established.
I have this happen when pulling my boat or other trailers in my pickup. Idiots are so impatient that they cut into my safe following distance. I generally try to back off to give them a bit of room, but it's not always the best solution. I think the idiot that cuts in front of something with as much momentum as a pickup/trailer combo or bigger is the bigger problem, since that individual was driving safely prior to the idiot cutting in front.
Now if the towing vehicle just happens to run up right behind you for no apparent reason, then that individual is the one who is causing the issue. In my experience it's usually the other way around though, the smaller vehicle usually has no respect for how long it takes to stop/slow a heavy vehicle, invades the safe following distance the driver had established, and then wonders why the other vehicle plows into them when they suddenly decide to slam on the brakes in a panic stop to get to their exit, turn on the next road, etc.
Often times I do get frustrated at idiots hanging out in the left hand lane travelling the same speed as those in the right hand lane. It is tempting to want to try and motivate such people out of the way. That is a law I would love to see enforced, the "keep right except to pass" thing. I don't care if you're doing the speed limit or not, you're creating an unsafe situation because other drivers will likely tailgate you and so forth. Not that it's right, but right or wrong it's what invariably
will happen. Why not just get out of peoples' way when the opportunity presents itself (this comment applying mostly to situations in which passing lanes are available).
As to the tractor on the road thing, it's sort of fun. I drove mine a few miles to do a little bush hog work for a friend, and even though it's mostly dirt roads on which I travelled, it was an interesting experience. I'd do it again, since it probably won't hurt anything. Let the cars do their own thing, and just to be courteous if you find someplace you can pull over if they can't safely pass when it starts to get congested behind you.