I'm not sure I understand how this is vote manipulation? Surely they are just replying to the "somebody should post this to HN" comment by showing that they did? Why does an image get illegitimate votes?
But even then that would technically be vote manipulation because it's drawing attention to an immature submission. (and there is little genuine reason to do so. The only counterexample I can think of is using HN as a comments section)
I am against vote-manipulation of course but I don't think that this is an instance of it.