Since there is no separate category for Remove from play then we must assume that to be Removed from play is the same as removed as a casualty.
Right I'd like to start by saying I'm not a necron nor SW player and I have not read the FAQ yet, so my reply will be soley based on the evidence that you have given and I am taking it as that you have quoted word for word, as this can make a real difference.
I answer the quoted statement with 'why must we?'
You seem to quote
"if reduced to 0 wounds or removed as a casualty for any reason we get our wbb unless it was double our str or a weapon in close combat that denies our save"However I'm fairly confident that this is not the exact wording. Based on my trust that you have given fair representation though I can say it is clear from JOWW that you are not being removed as a casualty or reduced to 0 wounds, you are being removed from play. Your model is being removed, there is no marker left for WBB, it is removed, not a casualty, removed.
However if this does not convince you, as I doubt it will, I suggest bringing it up on the rules forum.