I don't think this matters against the NSA. An adversary either has the resources to exploit some target, or not. If the NSA has a lot of exploits to choose fr

I don't think this matters against the NSA. An adversary either has the resources to exploit some target, or not. If the NSA has a lot of exploits to choose from for each of Linux, Mac, and Windows then it doesn't matter which one you're using. Think of this in Bayesian terms. You have some prior beliefs that MS W software is less secure than other software. What we've gotten as a result of all these leaks is new likelihoods, so we have to modify our posterior. I.e. A is more secure than B doesn't matter if both A and B are easily exploitable by your adversary.