I remember a talk of Crockford, where he explained that. He also explained that it worried IBM lawyers, to the point that he signed them a document "authorizing IBM to do evil with his software".
So great, anyone who asks for exception from the clause should be the next focus of the Surpreme Lord and Ruler (the US government)... no need to waste all this money snooping through people's email and facebook accounts!
Pretty funny nonetheless, more people should add these little clauses in :D
No they shouldn't. To you it's cute. To anyone who's serious about using JSON it's an arbitrary field of use limitation that could be construed to mean anything. In other words, it makes the software unusable for Real Work (TM).
(Disclosure: I am not a lawyer.)
If I was was Douglas then I would, at this point, refuse to change the license. If you don't want to use it due to some anal overpaid lawyer then your problem, use something else.
A lawyer may tell you this makes your software unworkable, but common sense tells me that this clause means jack all. As you say, it could be construed to mean anything and a court with any common sense would throw out any claim. It would be difficult to fully define the term "evil".
(Having said that, I understand it would probably cost a bucket load through the legal system, that same lawyer bending you over again)
An amusing anecdote none the less!