I should have clarified…flirting with people from work is not awkward or strange (though it is often a sign of bad judgement, IMO).

The manner in which he “flirted” was awkward.

Agree about the manner being awkward, but not about it often being a sign of bad judgement. Bad judgement is discounting someone because you happen to share the same office — shows a lack of open-mindedness if you’re both interested.