I am interpreting IlyaShpitser as commenting on OphilaDros's presentation; why say Ng "disses" UFAI concerns instead of "dismisses" them?
It also doesn't help that the underlying content is a handful of different issues that all bleed together: the orthogonality question, the imminence question, and the Hollywood question. Ng is against Hollywood and against imminence, and I haven't read enough of his writing on the subject to be sure of his thoughts on orthogonality, which is one of the actual meaningful points of contention between MIRI and other experts on the issue. (And even those three don't touch on Ng's short objection, that he doesn't see a fruitful open problem!)
My impression was that imminence is a point of contention, much less orthogonality. Who specifically do you have in mind?
http://fusion.net/story/54583/the-case-against-killer-robots-from-a-guy-actually-building-ai/
(An earlier version of this article was titled 'Andrew Ng disses UFAI concerns" which is the phrasing many of the commenters are responding to).