It made it to twitter or wherever, so it was noteworthy but nothing more. Also a way to show Q has access to multiple Trump family members I guess.
But Q said “What are the odds?”
That is the reason I think there is more to this than mere coincidence. Could be “who is stalking/following taking photos”, and is this person taking photos of Mueller or Trump Jr? But “what are the odds” really does seem as though it’s in connection Mueller and Trump Jr being in the same place at the same time.
It’s not just a random photo that Q posted for no reason.