I also have had issues with Thieme but I wouldn’t call him a nutcase. His teaching in the 60s was truly outstanding. He did get too oblique in his later years. It has happened to others. In my opinion Arthur Pink was a far superior teacher, far more grace-oriented, early in his career.
I had the displeasure of meeting Theime and certain people around him in the 1990s.
Never a more disfunctional group I have ever seen.
His opinions on abortions (he thought they’re just dandy) made me wonder about many of his teachings.
He was screaming at someone who dared look at his watch during a sermon.
Lacking understanding of grace and love, as you note, was a weakness. All about knowledge, little about ACTION.
In this Christmas/Chanuka season, I note that his house had nary a Christmas decoration on it — and that was back when he was healthy with his sons around to help.
In short, I really, really disliked the man.
He had an answer he would want and he would pluck scripture from here and there until he got to that answer.