Thought this was pretty funny, although I may have misunderstood. Regardless, I loved this piece.
So I think Rilke was saying he won't attempt criticism (won't talk about technical details such as rhythm or structure or vocabulary) because none of that matters until the poet has something to communicate (has found their voice, a style of their own) in their poetry.
For an athlete, it might be that it's not useful attempting criticism of the finer points of their checking technique ("keep your elbow further in during a shoulder check") if they haven't yet figured to skate to where the puck is going ("skating to where the puck has been" being equivalent to paying too much attention to what outsiders are saying).
Returning to the comics metaphor, imagine if Rilke were trying to nicely say "these model sheets you've sent are technically slick, but they all look like Marvel characters ... what do your characters look like?"
(at which point I guess Rule 63 might be the equivalent of the poetry exercise in the sibling thread: it constrains a lot of decisions as to style, tone, etc. yet the gender swap forces one to make decisions of one's own)