I didn't and don't agree with Menzies Campbell a lot. However, you can still feel for someone facing the sad fate of a political career ending not just in failure but in humiliation.
The closest comparison I can see is Iain Duncan Smith. Both of them fell as quiet men who just couldn't make it as leaders in the brash game of modern politics. That could be a reason to be optimistic for Menzies personally: It would be impressive if he can engineer a similar renaissance as a powerful advancer of a particular cause.
A lot of people are talking about his age. I don't think it was his age itself that did it. Michael Howard never faced the same ridicule and would not today (watch him arguing on TV) despite them both having been born in 1941. The problem was the same one faced by IDS. He just didn't have the charisma to lead. People will rationalise that charisma in many ways: Menzies it too old, IDS was too bald. Neither flaw was really the fatal one.