Harry is being an ass. Of course, he is thirteen.
Mike's taking Harry to church with him was a really good idea. The passage from the New Testament was particularly appropriate. Harry needed to see that he was being unnecessarily cruel to Luna. As he said, it was a prank they both would have enjoyed, had the circumstances been different.
A wonderful twist. I've read a few where the dragon willingly allows Harry to take the egg, but this is the first where she refuses (out of a sense of duty/pride) Harry's using the avis spell is also unusual.
As always, I eagerly await the next chapter of 'Luna's Hubby'. Alorkin