I think his timing definitely was to capitalize on his 15 minutes. With Walter's book coming out with an apparent axe to grind, he probably wanted to maximize his window of opportunity. He timed the release for the PGA and teased it up because he knows his thunder is short lived and not really that salacious as this was all previously known information except for the Saudi comments.
So there is some truth to this and it furthers my point that the information contained in the book is not solely responsible for Phil's withdrawal from the PGA. From what we know about Phil, he would have relished the defending champion role and would love to see how many under 50s he could have lapped (and would probably had some over/under action on that). There is more at play than what we know.