Ah those nine million things, is it a little bit like finding a tenner down the back of the sofa, you didn't even know you'd lost it, hurrah and let us congratulate these "heritage heroes".
But no, wait - actually it's more like me finding someone else's tenner down the back of the sofa, not telling them, and then running quickly off down the pub to spend it.
And whoever dug up the henge, they made the mistake of picking something that people knew was definitely there in the first place. Presumably Bad Detectorists use the justification that no-one ever knew their find existed to clear their conscience when they cling onto it (it's just in my pocket not in the ground).
I was sorry to have missed you the other week btw.