Unfortunately it is never guaranteed that the monorail will be up and running. It dose break down every so often. So if you are looking for an 100% guarantee that it will be up and running whenever you want it, then you are going to have to keep looking.

Everything at WDW is subject to change and availability. They do not guarantee a single thing.
I wonder too why you didn't just hop in a cab to get from the Contemporary to the Poly, if you needed to get there quickly. It couldn't cost more than $10. Using Disney transportation to get from one resort to another is never speedy, not even by monorail.
I have to add too that if you are stopping the park bus drivers and asking them how to get from A to B, then you are keeping them from doing their job. I know if I was trying to get on a bus, and someone ahead of me was preventing that because they wanted to have a long conversation with the bus driver, I would be kind of ticked.
I disagree respectfully with what I have bolded. Asking a bus driver how to get from point A to B is their job. It happens all the time, and the drivers are used to it. How else are you supposed to find out?
Occasionally they have cm's at the resort bus stops who are trying to get the right busses to the resort guests via radio but that isn't always the case that they are there. And again, would you consider asking even that person a "taking time away from their job" scenario? And who said anything about a long, time consuming question and answer session? Example: Somebody getting on the bus at Port Orleans to DHS asks the driver as they get on "hey we want to go over to Animal Kingdom later in the day from Studios, how do I do that?" Driver responds "there is a bus directly AK from DHS, its que #x and it will take you right there". That hardly kept anyone in line from making their reservation on time in my opinion.
Frankly I have personally asked drivers questions, and I have seen others do the same probably hundreds of times in our many trips and its never been an issue. I never heard anyone get upset, its part of the drill. As you say, no method of transportation at WDW is all that quick and this may factor into it but its hardly unusual. A bus driver doesn't just drive the busses and if he wasn't there to offer customer service in addition to his/her driving, then they'd have him in a soundproof little cockpit with a do not disturb sign on it.
And to comment on the OP's post, I will add that the right thing to do would be for Disney to deeply discount these rooms. Obviously nothing is 100% guaranteed but honestly this whole thing of its unfair to the starving children of the planet if any of us dare get peeved with Disney over their lack of customer service is getting kind of old on this board.
Bottom line to me is that even with bus service to the TTC, boats to MK, walking to MK from the CR and monorails running some of the time, this monorail closure is not fair unless the rooms are discounted to go in line with the lack of an amenity that is being paid for but not fully offered. And not being communicated to the guest.
For me personally my reason for staying at the Poly years ago was access to the monorail to dine at other monorail resorts and get to MK and Epcot via the monorail. The monorail is not always my favorite mode of Disney transportation which is why I don't typically pony up the money to stay at one, but if I do and its not working, I'd rebook someplace else. And if I had elderly parents and kids in strollers and this came up, via me finding out on a message board, I'd be mad as all get out. It wouldn't ruin my life and I wouldn't think of it as an international crisis but I'd be scrambling and figuring out what I'd need to do to make my trip work and I wouldn't be paying the top dollar to stay at the CR. Which may be the "cheapest" of the monorail resorts but its hardly a cheap place to stay.
Improvements and maintenance do need to happen but I just think that to most this is not acceptable unless they are getting a very deep discount and plenty of advance warning.