The very fact that the Daily Mail is using the quotes around vulnerable alongside middle aged man phrase shows that they don't believe a middle aged man can be classed as vulnerable i.e.
1. 'vulnerable' middle aged man = don't make me laugh, a middle aged man can't be vulnerable.
2. vulnerable middle aged man = factually he IS a vulnerable man regardless of his age.
If the roles were reversed, they would have no concern in stating she was a vulnerable woman that the male cop took advantage of.
Do they not think a man can be vulnerable in middle age? Does vulnerability not cover emotional or mental state?
She was also in a position of power.
It just feeds into the whole men being the devil narrative that's so popular today....