Wasnt Solozzo a top narcotics man?
Wouldnt his expertise and connections be vital in building the drug empire for the mob head(s)?

I think he would be given a pass for his Vito blunder and the "hunted one" speech was just for Michael. Solozzo didnt actually believe it.

From the look on Michaels face. Michael didnt believe that Solozzo believed it either.