Call me cynical, but having been around the block a few times when I hear "need" and "require" my brain translates that to "want" and "it would be convenient if". I've done my share of forecasting for investors and am quite confident that there is nothing in any startup forecast that could conceivably "require" Windows. I mean, absolute worst case, just use SQL.

The CFO just preferred Windows, that's it, I'd bet money on it.