They should man (WWJD?) up and go to the klink.
You have a point regarding any volunteers threatened with arrest. That would appear to be a violation of their Constitutional rights.
Perhaps more important, since the chaplains received any such orders from superior officers, those officers should be the first to hold the line pursuant to the oaths they swore.
It is clear to me the military at the highest levels should resist such directives from its civilian superiors, not just junior officers in the field.