As someone who used to write and maintain Windows FS drivers, I can 100% back up this statement from that thread:

At least the first part of bezelbum's answer is absolutely spot-on. I have never written a Linux driver and as such cannot compare the relative merits of the two OSes from this perspective but I suspect that the second part of his answer, where he talks about how difficult it is to write a safe driver, has more to do with how much effort people put into breaking it than with any inherent security. All the Windows drivers exploits I have seen were of an extremely convoluted kind. I mean, if people put the amount of effort to find that into finding similar vulnerability in other OSes, I would be very surprised if they did not find at least half a dozen.