SPlicing is an inaccurate word to use here.
They pulled the wrong file footage, so they SHOWED 9/12 while they talked about last Thursday’s rally.
When it was discovered, they apologized.
There was no active intent to “splice in” inaccurate footage.
The Left CLAIMED that live footage from the Middle East of muslims cheering on 9-11-2001 was “file footage”. It was genuine and distasteful.
If it was, in fact, just an error, and not deliberate, then it is excusable.