He skipped the photo op to attend an event for Medal of Honor recipients.
Check it out:

Former US President George W Bush reportedly missed the dedication ceremony for the National September 11 Memorial Museum because he felt the emotions his presence would stir would be too much.

According to the museum Mr Bush was invited to the ceremony, but his spokesman Freddy Ford said he was unable to attend because of a scheduling conflict.

It later emerged that the former president was in Bentonville, Arkansas attending a separate ceremony for 14 living recipients of the Medal of Honour. The event also raised money for the Congressional Medal of Honour Society and Foundation.