An what was DJT supposed to do about it? Put on his Superman cape and go rescue him or call in the troops, oops possse comitatus would apply and then the dems would want to impeach him. Oh I guess he is damned if he does and damned if he doesn’t.
It is up the the Speaker of the House to control the security of the capitol. He has no authority over the Capitol Police or the National Guard and neither does the Mayor of DC. He is only CIC of US Military.
I think President does have control of National Guard...However, I am not certain how involved he was in deciding to dispatch troops on January 6...