Now that's a stretch
It remains to be seen whether authorizing a study in any Department of federal government, whose end is a violation of Article 2 (2) of this treaty, is itself a criminal act... or whether it may be construed as a high crime or misdemeanor under Article II Section 4 of the US Constitution (which applies, by the way, to "all civil Officers of the United States" as well as the President and Vice President).
So, asking lawyers for a legal opinion may be an impeachable offense? Are you serious? In the end, all of this is about an opinion from some lawyers at the Justice Department.