I agree with you, mostly. The thing is, if I were at a funeral of a friend who'd done some stupid and misguided things, I'd keep quiet to the family. This make it difficult when it comes to Lady Thatcher, who did things I disapprove of, but I'd find it very hard to convince someone who approved of her. And I'd feel bad about making someone feel so upset at her funeral, where people are already likely to be upset.