I don't have any insider info, but just from having followed Miguel's blog for awhile, my impression is that the Netflix stuff is more related to DRM than anything about Moonlight/Silverlight. I believe it boils down to there not being a PlaysForSure (or whatever their DRM is called, hard to keep them all straight they are so similar) implementation available to them, particularly on non-Windows platforms.
While I don't have any intelligent thing to say about Moonlight and Netflix, I did want to point out that Netflix streams to a ton of disparate hardware (and OSes, including "normal" ones such as OSX). Thus, I get the impression this is a legal problem more than a technical one.
FWIW, Microsoft provides a Silverlight runtime for OSX[1]; for embedded streaming I assume they hand out crypto certificates on a case-by-case basis. So yeah, pretty sure it's a legal thing.
[1] although being located outside the US, I can only assume that this is what is used.
Up one level, BTW, is a discussion about his 20% project at Google working with (or against) clang. Also insightful reading.