Not exactly... this material is obviously dated before 9/11/01 (or shortly thereafter) when the Coast Guard was transferred from DOT to Homeland Security. They were one of the founding agencies of DHS.
(Not something I'm proud of, BTW...)
Again, the part I was correcting you regarded the
National Guard. I was trying to support and agree with you regarding the
Coast Guard.
The
National Guard is subject to Posse Comitatus when it is federalized, at least under current legal interpretations. The
Coast Guard is not subject to Posse Comitatus, but can be made subject to the Navy's comparable regulatory directive for any personnel who might be transferred to be under Navy authority.