More and more, companies are giving their sysadmins and coders Macbooks rather than Wintel laptops. It's been an upward trend in last eight or nine years. I've always thought it was to head 'em off at the pass so they won't install un-remotely managed and un-monitored Linux distros on company equipment. At any rate, a lot of proprietary stuff winds up on corporate Macbooks, which means targets worth going after. As for availability of exploits for OSX, folks have been hoarding them for this kind of situation. These days, you wait for an optimum target environment before you unleash your 0-days.