The SE guidelines point towards that answer having been deleted incorrectly
I suggest reading the following:
All of these promote not deleting answers solely because they have downvotes and promote deleting answers when they are not actually honest attempts at answers. To quote those links:
For answers, any post that is not an answer (should be a comment, doesn't answer the question, etc.) should be deleted. Answers that are wrong or that dispense poor advice should be downvoted, not deleted.
A wrong answer, downvoted, also conveys information. It tells you, the visitor: don't do this. This answer is wrong, and if you are lucky the comments tell you why it is wrong.
Answers that do not fundamentally answer the question may be removed. This includes answers that are:
- commentary on the question or other answersasking another, different question
- “thanks!” or “me too!” responses
- exact duplicates of other answers
- barely more than a link to an external site
- not even a partial answer to the actual question
As far as I can find, RPG.SE does not have guidelines or policies that supercede the general Stack guidelines.
We can compare RPG.SE to something like Skeptics where (according the their Meta welcome):
[...] Questions must be about a notable claim [...]
[...] Answers need references [...]
RPG.SE does not have similar requirements that I have found. We do have the following question:
And the answer there simply states:
[...] vote to undelete when you don’t think it should be deleted. [...]
I don't think this is any sort of fundamental change to deletion and undeletion across the site, but I thought that answer was worth mentioning.
The answer in question should be undeleted
The answer in question is not spam or anything similar. It is an honest attempt at an answer to the question. As such, it has no reason to be deleted. For me, improper deletion is one of the strongest reasons to undelete something. Keeping it deleted would promote similar deletions which we, as far as I can find, do not want.
That said, the post's own author may still choose to keep the answer deleted. If they do, I personally believe that that decision should be respected. But RPG.SE policies on undeleting posts deleted by their authors should be left to a different Meta entirely.
I personally cannot say why this answer was deleted, because I did not vote to delete it. It was likely due to the lack of citations, and posts I linked to earlier say that bad answers that are still honest attempts at answers should not be deleted. To me, the general guidelines lead to the conclusion that the post in question was incorrectly deleted and for me an incorrect deletion should be undone.
The general SE guidelines have some pushback
The previously linked posts are all in support of not deleting downvoted or flatly incorrect posts; meanwhile the following post also exists:
And an answer there states:
Yes, absolutely. That's why high rep users can vote to delete. That is also why there is a peer pressure badge, to encourage users to delete their own downvoted content.
We want to identify harmful answers, but we do not necessarily want them to stick around. Even though their scores are negative, even though the content might be grayed out, people can still see them, ignore the warnings (or not even understand them) and use the content. [...]
So not everyone agrees whether flatly incorrect answers are unhelpful or whether they should be deleted but the SE general guidelines state that they should not be deleted.
Perhaps worth mentioning, the Peer Pressure badge exists and is awarded when you:
Delete own post with score of -3 or lower
This isn't the same situation, since it's about the author deleting their own post but it could be construed as SE incentivizing deleting posts solely because they have downvotes, which would go against the general guideline. However, this badge also has quite a few Meta posts about it including