I always thought that Red went to Mt. Silver to grind, and while he was wandering around he got lost.
He was lost for so long that he finally got tired of encountering wild Pokemon, so he used up all his repels trying to find the exit.
He wandered around for so long that he eventually wound up at the very top of Mt. Silver, and he's looking over the edge like "God damn it, I didn't bring a flying Pokemon."
And then Gold goes up and fights him.
And then Red remembers that he actually had an escape rope the whole time, and he's so embarrassed that he leaves without saying anything.
