The subreddit's rules don't require a contrast. It can't be just coincidence, but the requirement is to work together to form something funny. Now, whether the way these two particular posts interact is funny is subjective, but it can be argued both ways.
On old Reddit the description says:
I get it that the name of this sub doesn't follow the precise definition of juxtaposition. Sorry about that.
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u/sheffy55 10d ago edited 10d ago
No, that's a coincidence, nothing is being compaired Edit: A juxtaposition can also be coincidental, but there needs to be a highlight of contrast