It isn't Trump's job to judge what venue is correct and what cause is correct; that job is for the courts to decide.  His job is one thing only related to the Constitution:  uphold it and ensure citizens are protected by the rights afforded by it.  That's not obfuscation.  When he starts deciding when and where those rights apply would be obfuscation.  

Yep, you can be fired. And, you could take it to the courts.  You might win; you might lose.  But, that isn't Trump's job to decide.  There's a separation between the Executive branch and the Judicial branch.

Trump is plain and simply breaking the promise he made under oath, and just like with slick Willy, that is indeed an impeachable offense.

Oath:
""I do solemnly swear (or affirm) that I will faithfully execute the Office of President of the United States, and will to the best of my Ability, preserve, protect and defend the Constitution of the United States."[2]"

Pretty simple.