Yea I don't think Pistone knew about Scarpa and no way Scarpa knew about him. I think at one point the Feds even had a file on Brasco because they thought he was a true player. They couldn't risk letting anyone in the FBI knowing he was undercover because if his name leaked he would have been dead for sure. I forget where, it might have been with Jimmy the Weasel and someone in Cleveland having a leak with FBI files to the gangsters that almost got him killed. The same could have happened with Pistone if it was well known with the Feds that someone was in with the Colombo's or Bonanno's.

Also I don't find it odd he wasn't around Massino much. I can't remember once again where I read this, but someone was complaining about they didn't know who the boss or their capo was and couldn't point them out if they were standing in front of them. Now that is some insulation. So if that was true at all then I don't find it surprising Donnie never was around Massino much.