It's a line I used many times to describe my old friend's standoffish behavior with younger dogs.
With dogs of equal "speed", he was always fine. Shy at first, but when push came to shove, he'd manage a few short wags before moving on his way when meeting another dog.
I got him when he was already a senior pooch, so there's little telling what his younger days were like or it was his ailments that made him who he was or his time in the shelter.
That said, in hindsight there were signs that I could have used to better predict that his arthritis and hip dysplasia were becoming more troublesome.
The first was his change in sleeping accommodations. Where he originally liked to sit in his big fluffy bed, he began to sleep more and more on the floor or on an older, flatter bed that I had in my back room. Towards the end he had issues standing up. The depth of the bed was obviously a chore for him to navigate.
This tracks with his feelings about younger dogs who would try to re-introduce him to jumping around. Since he couldn't get out of the way of the many 20 lb. puppies, he hide and get just nasty enough to keep them from getting to close if we were unsuccessful in keeping our distance.
He would also tend to walk along straight lines in the pavement. Straight lines with no obstructions are predictable. They're easy to use as a guide. His eyesight was decent and never changed from what I could tell, but at night he used to have problems with shadows. From further away he'd sometimes approach shadows carefully when we were in a location that he wasn't familiar. Once or twice he stepped to the side to avoid them, walking sidelong into a car bumper.
For dogs that are losing their eyesight, I'd recommend not making many changes around the house. Rearranging the furniture is going to take some time to get familiar. Expect that they're going to slow down until they figure out alternative ways of navigating.
A loss of hearing is another issue that may cause an otherwise calm passive dog to act schizophrenic. If a dog can't hear, it's going to be surprised if you walk up on them from behind, even if you've done it a million times before. Take the time to work out hand gestures to replace verbal commands.
Slow down, have patience, and take your time getting reacquainted with your senior dog all over again. They'll appreciate the extra attention.