When I hear 'passing on your left' or the like, and I'm riding as far to the right side of the road as is safe for me, I do not change position at all. I will not ride into glass or hazardous gutter situations, as it's the responsibility of the passing cyclist to not only call out their presence and intentions, but to also check the road conditions (meaning traffic in both directions, any obstacles up ahead, etc) to ensure that they can safely pass the cyclist ahead AND move back into the cycling lane without cutting off the cyclist they just passed.
When I first started road riding, I was lucky enough to ride with, listen to and learn from generous teachers/mentors who were learned veterans of ultra-marathon cycling events, including RAAM riders, women's TdF, national downhill champion...I still hear their advice when I ride!
I learned that the rider who wants to pass bears all of the responsibility and they should not expect that riders in front will get off the road, move over into unsafe conditions, slow down or anything else in order to assist them in passing. When I rode in my first organized century however, I did experience lots of faster riders and pacelines wanting to just ride in the middle of the traffic lane pretty much all of the time, blowing past any/all on their right whether or not there were cars back and yelling 'on your left' insistently at me, so that I felt intimidated. After these situations I asked more experienced riders and cycling coaches too; everyone essentially said the same thing: if you're riding as far to the right as is safe for you and holding a steady line, you do not have to do anything differently and consider the call of "on your left" to be an alert so that you do not pull out into the lane in order to pass anyone yourself, until it's clear.
Most of the states that I've done rides in stipulate single file on roadways, but I see otherwise all of the time. It's pretty dang hard to get past them when you've got 2 roadhogs ahead of you, as you had and I probably would've called out 'on your left' a couple of times, then snuggled up behind them and called out a polite request to allow me to please pass them safely. It sounds like, from your account, that they were fully aware of your presence though and it's outrageous that they'd create a situation where you felt as though you had to go on the other side of the road and on a blind hill - yikes! - in order to get around them. Some people have no brains and no heart and it seems as though you encountered the cycling idiot jackpot there!
Tailwinds!
Mary