Yes in my opinion, and I don't think I'm alone on that.
Indeed, it seems a great many people who dislike Murdoch and are on the left of the political spectrum seem to agree with you. I am sure however that none of that is at all relevant.

Did anyone else in the committee room feel the need to assault the man? People were up before she was, and in place (between the victim and the attacker) before she was. None of them felt compelled to lower themself to assaulting someone, so why did she?
The whole thing was over in a second or two and she had a particular attachment to the man. From a legal point of view as long as she honestly believed he was in danger then her actions can be classed as self defence.
The points you raise are all valid yet you know I cannot answer them, nor can you, but this doesn't dectract from the fact that this was not in defence of someone else in the legal sense the threat was over and had been mitigated.
Walking across and hitting someone because of what they might have done in terms of the substance isn't self defence, this is plain silly, it's assault. Retaliation, anger what ever you want to put it down to.
As long as she reasonably believed there was still a danger then it can be self defence. Considering the time frames involved it is not unreasonable to think that she could feel that way.
Had been assaulted, not 'was being' because the pie had been shoved on his face and he had been pulled away by this point.
Personally, of course. Heat of the moment, anger dismay love and concern. What's getting my goat is people demonising him and turning her into a saint.. on a level of reading this all off a black and white page they both committed assault.
Well no, because she could possibly fall under the reasonable force section of self defence and he cannot.