The Cheyenne would have been "cutting you off", if he hadn't "established otherwise"worked it out with the aircraft in the pattern and maintained visual separation.
According to the AIM, 4-3-3, standard pattern entry at an uncontrolled airport is abeam the midpoint in the downwind.
- Enter pattern in level flight, abeam the midpoint of the runway, at pattern altitude. (1,000’ AGL is recommended pattern altitude unless established otherwise. . .)