Your ending to your post was objectionable to me.
Did I say congress had a say in JAGS and/or who can legally fire them?
JAGS are not part of leadership. They rule no one. They are neutral, and only advise on the constitution and what is legal or what is not when it comes to military actions the Generals or Commanders ask advice on.....and those with years of constitutional study and experience are the most valuable. They stay and advise the military regardless of who holds the presidency.
But not to Trump....the constitutional legal expert, is who he fears will get in his way....