I've just had an idea.
Can you just remove the offensive bit of the post.
So my first deleted post (which sent this all mad) read:
"Your last few posts have made you out to be a right pompous ass 
"My child is not disappointed now nor will he be in the future, you kids will and not just about santa" is a really stupid thing to say. All children will be disappinted by various things at some stage in their lives.
I presume you will sit watching videos and telling them that characters aren't real, that you will only read factual books not novels, in case they believe the books are real hmm.
Father Christmas in most families is a bit of fun. If you don't want to do it, fine, don't, but don't think you are in some way better than everyone else because you aren't "lying" to your child. What a load of bollox."
So you could have deleted the first pompous ass sentence. I really don't believe it was offensive enough to be deleted. And certainly the rest of the post wasn't offensive at all (I think). So there was no need for deletion.
Maybe you need a "message edited by mumsnet to remove offensive part" or "message deleted because the op didn't like it".
That would be more accurate.