I think that line about Rocco building a secret regime was careless writing. Rocco was Clemenza's man, not Michael's. And it would be difficult for Rocco to build a secret regime under Clemenza's nose without Clem knowing about it. Since at that time Michael didn't know who would betray him, it would be a signal to Clem that he didn't trust him.
Very difficult indeed
Besides how would Rocco explain his absence / having little to no time for any jobs Clemenza would have wanted Rocco to do....
couple more threads [could be others] which maybe of interest
Secret RegimesRocco's secret regime
