You are correct on that. I see no problem with doing the ground rods at each unit, spaced 10-12 feet apart. Probably better to just go with the MDU setup. That way if anyone else wants Direct, you already have the means of delivery.
Of course you run into those situations where you have some old lawyer or someone that is stuck in the old ways on the HOA board, that starts to get scared about having two providers, or due to mental conditions, a board member or board members, may think that this is going to cause a problem with having both, and not really understand how you can have two providers at the same time to the building.
It comes down to education, education, education. I think that now we are all on the same page, and in the same agreement of the best route for everyone in that building to go.
The OP really does not have to be there for this to be done. They would just need to appoint someone by proxy, to act on their behalf, to go in front of the HOA board if there is one, to go over this plan, in how to make this work, so they can have DirecTV, even though others may not.
It is just the idea that everyone will think of, is who is going to pay for the materials to do the ground bond across the back or front, and how would it blend into the building, so as not to be easily seen (ie conduit that the wire may be inside of to protect it from damage).
When we moved into this place. The telephone & catv were on the South side of the house. The Electrical entrance was on the West side. The cable line was grounded on the West side, but they ran the coax all the way about half way down the South side, to where it entered where the antenna that was still attached to the house. The telephone NID, had its ground on the cold water pipe for the Kitchen faucet.
I ended up moving both of those services to the West side of the house, where the Electrical service was, so I could ground it to the ground rod for electrical. I still have to move the Comcast ground for our Internet, to a split bolt on the ground wire, that attaches to the ground rod. DirecTV was able to bury their ground, attach to the ground wire with a split bolt, due to it was not the middle of Winter, unlike Comcast.