It's not difficult to deduce what kind of a response to the implication question is a socially acceptable one.
If you are saying that he can figure out whether lying or telling the truth about his implication is socially acceptable, sure.
The real problem is that he already had an implication, but he's using the fact that it's an implication to maintain plausible deniability by not coming out and saying it. Saying it may be socially unacceptable, but that's because making the implication is also socially unacceptable.
It seems to me you've already decided what he was trying to imply. It might not be wise to do that based on such a simple remark.
If he brought it up to point out there should be more women on the list, you've likely just lost an ally. You've pretty much also lost the opportunity to make that point to anyone who noticed your prejudice.
Here is the 2013 edition of the Best of Rationality Quotes collection. (Here is last year's.)
Best of Rationality Quotes 2013 (400kB page, 350 quotes)
and Best of Rationality Quotes 2009-2013 (1600kB page, 1490 quotes)
The page was built by a short script (source code here) from all the LW Rationality Quotes threads so far. (We had such a thread each month since April 2009.) The script collects all comments with karma score 10 or more, and sorts them by score. Replies are not collected, only top-level comments.
As is now usual, I provide various statistics and top-lists based on the data. (Source code for these is also at the above link, see the README.) I added these as comments to the post: