I don't believe that's so. You may be conflating two separate situations.
Pagliano got an immunity deal from the FBI and I believe he has been cooperating with them accordingly.
A congressional committee then called upon him to testify -- and he refused to do so. That's within his rights since his deal was with the FBI, not Congress.
I believe Pagliano was given immunity in a deal with the Justice Dept. That should tell you everything you need to know. Loretta needed to give Pagliano the excuse he needed NOT to testify before Congress.