According to his Nat'l Guard GO bio:
He entered service in 1979, so he is waaaay beyond the 35 year total military service law (unless waived by Congress as in Rickover); probably his Guard time played with that calculation.
The TAG of the DC Guard, unlike states' Guard which are appointed by the respective governor, is appointed by the President of the United States who is currently, and was when this order was given, Barack H. Obama.
The MG is also 65, again a mandatory military retirement age unless waived by Congressional action.
Nope, it's Trump's fault.
We're gonna see a lot of that, I reckon.
There was a good column (forget the venue and writer) on how everything for the past eight years was Bush's fault, and from here on out everything is Trump's fault.
It's as though the last Administration didn't exist.
Sure must be nice...