Dealing with Answers that should be comments

Question

I realise it's a deficiency in the SE system, but a new user (from memory) can't post comments to questions or answers, unless it's their own.

A lot of users throughout SE as a whole do this, post an answer that really should be a comment on a question or the answer in question because they can't offer said comment because their rep os too low.

How should this be handled?

For example, in this question:

error: redefinition of ' '

There is a down-voted answer which someone else has come out in support of (rightly or wrongly) but can't add a comment because their rep is 1. But in the scheme of things, if this is in fact valid, then it could serve as a valuable comment and aid to future searchers.

For the interim I am going to manually create the comment for him and recommend his answer for deletion, but I'm open to suggestion on what the "norm" is

Answer 1

Flag it and let a moderator take a peek. We have the tools to directly convert an answer to a comment (so that it looks like it was posted by the user who posted the answer) or delete the post altogether. We also have the know-how to properly respond to the user to educate them about Stack Exchange and its practices.