It should be possible for an admin to comment on a question that's "Awaiting approval" without having to approve it first.
Specifically, the use-case I envision here is when it's unclear what the post is suggesting. I don't want to approve a suggestion and later find out it's a duplicate of an existing one - and I don't want to split a suggestion that seems like it's suggesting multiple features, when in fact the post author is simply describing a single feature in a confusing way.
The other primary situation where the ability to comment would be useful is when a post is not actually suggesting a feature, but rather reporting a bug/error, or asking a customer service question, or giving feedback on Feature Upvote itself. None of the current statuses make sense for this situation (not even "Not planned"), but there's no way to respond to the post author without approving the suggestion first. (Alternately, this situation could be handled by adding a "Not a feature request" status...)