If you wear your super classy outfit to an interview AND you have the iPhone 5 instead of a prepaid Android phone (or worse -- a prepaid non-smartphone), it's going to show that you "belong" and that you're not poor.
Some people really do pay attention to what kind of phone you have, particularly for these gateway-straddling jobs that the author talks about in the article.
A smart phone is a valuable tool for a professional. Being able to send an email or call from the road when you're running late, or to receive same when your counterpart is running late - people expect this nowadays.
Of course, during the actual interview, it should go without saying to put it on silent and leave it in your pocket or purse.
It would be cheaper to look for a job in an environment that is more interested in what you can do rather than what you tote.
That is, after all, what most of us end up doing.
This is what I'm trying to get across with my posts on this topic.
People keep using reasoning from within a higher-class group where you already know the rules and assumptions of the game. The whole point is that the people below don't.