Him assuming the office of the president is legal. But him trying to replace the law which has gone through due process using executive orders is unlawful.
It is not a coup because he became president by force. It is a coup because he is consolidating power. (The president is not supposed to be all powerful.)
The Wikipedia-article explains why "consolidating power" as part of the government is Gleichschaltung and not a coup. A coup is the sudden, violent, and unlawful seizure of power from a government [1] which is not the case here.
No one is going to start calling this Gleichshaltung, so stop trying to make it happen. Words can be flexible. The current situation approximates a coup, and so people will call it a coup. Honestly, splitting hairs over definitions while our government is being stripped for parts? This is part of the problem!
