Okay, so it sounds like the owner of the boat was okay with the boat being moved, so in this case it was fine, but it also sounds like that might not always be the case. In those situations, I would probably err on the side of caution, but I don't know what that would have meant for you.
The next thing is, it sounds like mooring up properly is the main issue this go around, so if that was done, again not an issue.
Was the motorboat that was moved in the wrong place to begin with? Is there an expectation that three boats will be moored there?
This being a breakwater (and without water and electricity) it's actually the quay of the last resort, with an expectation that it won't be used muchexcept for shorter stays. The motorboat was in it's perfect right to moore up as he did, and it would have been space for one more boat there had it been the same size as the motorboat.
I usually try to make as little space as possible to the boat in front when mooring up, but there are some disadvantages:
Even if one ensures the distance is as small as possible to the next boat, there will eventually become a gap when the boat in the middle leaves.