I don't necessarily agree with all of this analysis. I think the more likely reasons are that it's very easy to be against the war when you are not in power. But once you are in power it's not sufficient to be against it, you need to work out what you need to do instead. And then you run into the reality that even though you don't agree with the war, the previous government did it for reasons. And even if the response is not what you would ideally have chosen many of those reasons are still valid.