Kaminsky stretches the floor about the same as Theis does. Difference being, Theis is much more efficient shooting 2's, is a much better rebounder, rim protector screen setter and Theis actually plays defense.
The team already has three bigs they are trying to squeeze into two rotational positions. Kaminsky is not needed. I could not care less that he is 7 feet tall. Grant Williams, Theis, Thompson, Timelord are all better players and Semi hits threes more efficiently and is a very good and versatile defender.
There is a reason no one wants him.