I strenuously disagree.
He was clearly in love with Heather Mills.
First of all, she was 34 when they got married.
If McCartney was in it for "young stuff" he could have easily have married a much-hotter-than-Heather 20 year old with two legs who was willing to sign a pre-nup that capped any potential divorce settlement at a few million pounds.
He obviously married for love.
34 is young when you are 60 and then some.