After the actual swearing-in ceremony, we left the Mall area for distant Red Line points in search of warmth and food. En route to the bar, we discovered the reason for the occasionally empty bleachers we later saw on the bar TV: DC crowd management was pretty broken, and apparently had last minute changes not documented in any of the publicly available info source.
Consequently, it would not surprise us to learn that some of those bleachers had become inaccessible islands, with their ticket-holders trapped elsewhere with no way to reach their seats. We have several friends who couldn’t get in (we did, though) despite having tickets owing to the enormous crowds and perhaps questionable crowd-routing choices. Granted, there’s not a lot of precedent for 1-2MM extra people in a town this size, but it was still frustrating.