You are correct. Any idea why President Trump ordered military troops to DC?
1) Trump will order them to arrest Biden and Kamalla.
2) To cover his butt against any violence that might be caused by radical, 50- 70 year old right-wingers.
3) To protect Biden and our government against left-wing BLM and Anti-FA groups that are planning a false-flag riot based on intelligence information.
(I’m going with #3).
Number 2 is still a bit in the future.
I'm not an insider, so no, I don't know why this was done in such overwhelming numbers.