Not "for Obama" per se, but yes otherwise. Of course they would.
I don't know if federal troops were involved in any of the efforts to disarm the law-abiding residents of Louisiana in the Katrina recovery effort.
-- Would other military units defend citzens being attacked by special government units? --
No. Some individuals in the military may shed the uniform (go AWOL) and switch sides, but there will not be uniform v. uniform action.
Civilians should give the military the same amount of trust ATF, FBI, IRS, and other assorted federal agencies have earned. The degree of trust should not be adjusted up or down depending on who occupies the White House.
bump