There are Twitter posts saying that it is against the Special Counsel statute to appoint someone from government to the role.
If this is true, can Trump go to Court and have Jack Smith removed?
Laws passed by Congress are in the United States Code.
The Code of Federal Regulations is stuff made up by bureaucrats in their spare time. The Special Counsel is in the CFR, which is subject to bureaucratic whims. It’s not law.
The reference to ‘outside the government’ is probably a copying mistake. Adding someone with full US Attorney powers would likely require Congressional action or Senate confirmation.