This is the part you are missing: "high crimes and misdemeanors" mean whatever the House wants them to mean.
High Crimes and Misdemeanours are defined in US statutes and precedent where a 2/3 vote after the proceedings are completed will determine guilt or not. In full the vote will be whether or not treason, bribery, and other high crimes and misdemeanours were committed.
http://www.crf-usa.org/impeachment/high-crimes-and-misdemeanors.html
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And more to the point, JOHNSON WAS IMPEACHED on that article. Conviction was a separate issue from "CAN THEY IMPEACH THE PRESIDENT FOR PISSING OFF CONGRESS?"This is the part you are missing:
Only if this fell within treason, bribery, and other high crimes and misdemeanours.
High crimes and misdemeanors are no where defined. They are whatever the House says they are when they vote on articles of impeachment.
Johnson giving speeches which tend to cause disrespect of congress was declared a high crime and misdemeanor because the house voted to impeach him for it.