Note that the article author is the author of TextSecure http://en.wikipedia.org/wiki/TextSecure It's not surprising that he prefers TextSecure over GPG in the context he explains:

"introducing private communication(...) for casual correspondence with strangers."

It's obvious that author prefers his chat for that. Still there are scenarios where the GPG wins over chat. But it's also true, most people would make serious errors if they'd try to use GPG.