She wasn't a volunteer, fella, she was bestowed with immense wealth and privilege as a result of that service. Effectively, it was her job. As a consequence of that job, she was able to give away £12m to protect her son from facing court. In my view, that is not a good look.
I absolutely respect your point that a mother will do what they can to protect their children, so I do not think she is entirely to blame here. He brought this on and appears to have repeatedly abused trafficked minors supplied to him by a convicted sex offender. If this were not the Royal Family, I suspect many more people would not dream of defending them. She may have been a fantastic woman - I have never met her. She may have been highly skilled at her job - I don't know enough about her job to analyse her skillset. She did, however, raise a family who appear not to respect their roles, their marriages, or their debt to the nation.