TLK didn’t say it was okay for married people to flirt with others besides their spouse. He mentioned in his post that seeking such “validation” whilst being married is a negative thing.
What he was trying to do was…attempt to come up with the possible psychological motives behind why some married people feel the need to flirt.
You will even find articles on the Internet attempting to explain the plausible reasons why people have extramarital affairs…commit crimes…are abusive, etc etc. It doesn’t mean that the writer agrees with the reasons or is trying to justify them. It simply means that the writer is attempting to understand why a situation might be taking place.