Doesn't rule out stock options...
Not being publicly traded doesn't rule them out entirely, it just makes them a hell of a lot more difficult to value and monetise.
There are other options as well of course. As small slice of the pie from his division could be lucrative and potentially much more motivating since he isn't bouyed up or weighed down by the rest of the company.
Or there could be non-financial factor. Perhaps he really, really, didn't like that bitch working as his PA. Or the brand of cola in the vending machines at Cisco. Or the way the sun shined in his eyes in the mid afternoon when he was sat at his desk. Or Dell offered him something he felt he could get his teeth into.
Yes, I'm getting silly now, but it doesn't necessarily have to be about lining his own pockets. It could well be, but likely we'll never get to the bottom of it - that obscurity is one of the benefits of being privately run.