I posted on another thread that it seems to me that the appointment of Mueller is against the IC 'law'; the IC is supposed to investigate possible crimes. Since collusion is not a crime - does Mueller have proper legal standing to prosecute any crime he wants to? ...like Michael Flynn, Paul Manafort, et al? Is Mueller now the new DOJ?
Manafort is making an argument similar to those lines.
Manafort seeks dismissal of D.C. Mueller indictment - 03/14/2018
The contention you make is even more broad, and is also well taken. There is no such thing as a special counsel for a counterintelligence investigation.