Right, storing your code anywhere presents risk (including self-hosted on a FOSS stack). With GitHub/MSFT, that risk includes "they decide they don't like you anymore" amongst others. How high is that risk? You'll think it's a lot higher if GitHub were to kick off ICE.
(disclaimer: I hold a small amount of MSFT stock, though this was not on my mind when I wrote my original post - thanks for the reminder).