Hmmm. I guess I'm the only one here not having a huge issue with what Gilliam said. I more see it as Gilliam is upset at the loss of Ledger, and Gilliam seems to think the relationship with Williams was what started his downward spiral. So, he's sort of lashing out at her, and also airing lots of dirty laundry that maybe nobody knew about.
Don't forget Gilliam also worked with Ledger on The Brothers Grimm, before Brokeback, before Williams, before the Joker role, etc. I can imagine it's hard for someone as a director and a friend, to see a good actor and friend beforehand, and then watch them go downhill... IMO, In lots of ways, Gilliam is defending Ledger quite a bit in this article.