You missed the sarcasm in the post. Since he didn’t want his middle name used during the election, but then used it for taking the oath, it’ a way of now emphasizing his “Moslem” roots.
There’s a difference between using your full given name while taking an oath, and having political opponents emphasize (”Barack HUSSEIN Obama”) your middle name as a slur. Unless you heard people on the campaign trail regularly refer to “John SYDNEY McCain” and “Sarah LOUISE Palin” from the stage, then there was a slur intended in the exaggerated use of his middle name. Intent matters. Using your own full name in an oath is different.
If the pix doesn't come through, here's the link:
http://www.bittenandbound.com/2009/03/01/roxana-saberi-former-miss-north-dakota-detained-in-iran-photos/
America journalist Roxana Saberi, 31, was arrested and detained in Iran