Perhaps this is all over blown. I recall seeing two seats up front held for a while after Nancy, Patti and Ron arrived. Then people seated behind moved up to avoid leaving a conspicuous absence. My thought was Michael was held up in traffic and therefore stayed at the back after he arrived in order to not cause a disruption as people were shuffled around. At least that is my "glass half full" explanation to counteract the typical "half empty" spin.
That's possible. But it still seemed funny that he wasn't hardly ever with the family.