I agree with Gowdy. If Rosenstein is keeping info from Congress, then let Trump release it. If Rosenstein is acting unethically, then let Sleep Jeff Sessions or Trump fire him.
Rosenstein is impeding and obstructing Congresses oversight responsibilities and duties so it is well within the purview of the Congress to do due diligence and impeach him for his deliberate obstruction tactics as he is required to do by law. Don't try to lay this off on Trump.