I think he is saying, and I agree with him, that Diana had an unfortunate habit of acquiring the most unsuitable people to go to bed with, to confide in and generally to hang out with.
OK she was the acceptable sacrificial virgin that had to be found to provide an heir for Charles but given all that would have been hers with a more careful choice of confidants and a little dignity and she would still be enjoying it whilst looking forward to being Queen. Bedding half of the Household Cavalry and sundry others was not a wise choice and bleating her troubles, real and imagined to any passing Arab, poofter in waiting and journalist was even sillier.