It seemed odd to me that this answer was deleted. It was on topic, non-spammy or abusive, and while it didn't add that would be actually helpful to the conversation, it seems like that would be better handled with a downvote and a comment.
That answer was posted by a sockpuppet account of a known problem user who is currently suspended from the site. This user has been a prolific creator of unregistered sockpuppets, and this behaviour has continued even after their suspension. These accounts always have identical or near-identical IP addresses, making them very easy to identify.
Previously, we were deleting these sockpuppets on sight, but allowing their posts to stay as long as they weren't inherently delete-worthy. However, after discussions with the other mods, we have come to the agreement that leaving their posts untouched is allowing them to get around their suspension without any real consequences.
Therefore, for the remainder of this user's suspension, any answers they post using sockpuppets will be deleted on sight, along with their accounts. I realise this may sound a bit draconian, and we may consider abandoning this policy if the community finds it objectionable, but we really don't want this user to be able to continue flouting their suspension as they've been doing until now.