*Part of* [my answer][1] to https://meta.askubuntu.com/questions/5776/what-to-do-with-questions-whose-op-hasnt-visited-the-site-for-a-long-time addresses the core question here.

> ###Is it answered in comments?
> 
> If there are comments that effectively answer the question, or that
> *may* answer the question and may be helpful to others, those comments should be (or should have been turned into) answers! In this situation
> it is appropriate for you to answer the question with information from
> the relevant comment(s). You can even quote them directly. Just make
> sure it's clear who said the valuable words (unless they've explicitly
> made clear they do not want you not to cite them, in which case, still
> make sure you're not passing off their words or solution as something
> that is solely your own work).
> 
> In this situation, it's common for short answers based on or quoting
> the comments of others to be posted as *community wiki*. I'm not aware
> of any consensus or policy *requiring* this, but it often makes sense
> for these to be CW answers because:
> 
> - CW status clarifies that the person who posted it is not necessarily its primary author.
> - It's [easier for users with lower reputation to edit CW posts][2], as only 100 reputation is required to edit without going through
> review. That's especially valuable here because often someone posts an
> answer in comments instead of as an answer when they feel it's not an
> adequate answer, or not detailed enough. Thus it's especially valuable
> for these answer to be easily expanded by anyone able and willing to
> do so.
> - While you should not post any answer you think is meritless ("crap"), you might not want to associate yourself with this answer as
> strongly as usual. You might be unsure if it really works, for
> example. Posting it as CW sends less strong a message that it's *your*
> answer.
> - You don't get unnecessary negative reputation for the answer. You've posted the answer as a service to the community, but it wasn't really
> your answer. Posted as CW, downvotes will have no effect on your rep.
> - You don't get unnecessary positive reputation for the answer. Posting a valuable answer from comments is a useful service to the
> community, so it wouldn't be inherently bad for your reputation to
> increase as a consequence. However, you might *feel* you don't want to
> get reputation for it.
> - Votes are entirely about the answer, and not at all about your contribution. This relates to the last two points. Since votes (up or
> down) have no effect on your reputation, *people may be more willing
> to vote based solely on what they see as the value or usefulness of
> the answer*.
> - You can campaign for upvotes without violating etiquette. Upvotes on an answer helps remove a question from the "unanswered" list. (This is
> what people are usually talking about when they say "VTR" or "vote to
> resolve.")
>     - Of course, as in other situations, people may choose not to vote on any post; always remember that people's votes are their own.
> - You still get recognition. Besides your name on the post (or in the edit history), and the community's knowledge that you helped clean up
> and resolve questions, remember the system awards badges for CW
> answers (same as regular answers).
>     - The [revival badge][3] is frequently awarded.
> 
> Sometimes it makes a good deal of sense for a post based on someone's
> comment *not* to be community wiki. If most of the content is your
> own, or you've extensively expanded, beautified, corrected, or
> customized the post. There's no clear line where it should or
> shouldn't be CW, and you're unlikely ever to be criticized for too
> many of your answers being community wiki. But you should feel free to
> post non-CW answers when you feel it's "your answer."


  [1]: https://meta.askubuntu.com/a/5781/22949
  [2]: http://askubuntu.com/privileges/edit-community-wiki
  [3]: http://askubuntu.com/badges/62/revival