It is common for many functions to run late by several minutes. But this was no ordinary event — it was the inauguration of the President. The constitution says that the President-elect becomes President — oath or no oath — at 12 noon. And what was happening at 12 noon? Yo Yo Ma was playing Cello along with other musicians. What was Dianne Feinstein doing? Wasn’t she in charge? At 11:55 am should they not stop whatever they were doing and administer the oath to Obama? It seems that this has happened at the inauguration of 2 other Presidents.
If anybody is expected to know the Constitution, it has to be the Chief Justice of the Supreme Court. And Chief Justice Roberts had only one task — swearing in the President — for that day and one that should take no more than 30 seconds. And he flubbed it — while the whole world was watching. And it is not as if Roberts is 80+ years old like Justice Stevens (?) who administered the oath to Biden. Roberts is 53 years old. On the advice of Constitutional lawyers, Obama took the oath again, from Roberts, in a private ceremony at the White House.