I don't know Hans Passant, but he's the 5th highest rep user on SO, and I'm sure that's no fluke. He clearly is very active and knows what he's talking about.
His answer to the question at VB.NET - Interrupt form loop and end form did not satisfy the OP. He asked for the answer to be accepted and the OP declined. So what?
In steps Reddit. Someone made this post linking to an image of the "offending" comment (image at http://i.imgur.com/lKr4L.jpg, comment has been deleted in what I assume was an attempt to end the onslaught of downvotes).
This reddit is the top post on /r/programming, which is read by quite a few people. Hans got -70 votes (he just deleted his answer), a mediocre question got 26 upvotes, and a mediocre answer got 41 upvotes.
Is this fair? Is there anything we can do to restore some of Hans's lost rep, or right the balance of the SO universe? It seems like the users who engaged in mob behavior abused their ability to vote down.