I do doubt that the fact he worked for MS has very much to do with all this (although talking to MS ppl might have changed his opinions on things and the like).
Ok, I don't know, but it's not really needed to explain his behavior and as such I simply go for the simplest explanation: he just wants attention. Which works exceptionally well. Realize that this is typical FUD: only those who know what they are talking about (the average LWN reader, for example) know it's bullshit but 90% of the readers of his blog will probably take it as an insightful article by a good and clearly smart lawyer ("let's hire him to defend us/check our legal situation/etc").
Frankly those who think MS is behind this (same as with SCO) imho greatly over-estimate the intelligence of large corporations. This is too cunning a plan to come out of a bureaucratic entity as big as MS.