Wasn't Asimov a science fiction writer?

He was a popular writer of both fiction and nonfiction, had a PhD in chemistry, and wrote on numerous topics, including science, history, Shakespeare, and the Bible.

He and Arthur C. Clarke had a (tongue-in-cheek) agreement:

The feelings of friendship and respect between Asimov and Arthur C. Clarke were demonstrated by the so-called "Clarke–Asimov Treaty of Park Avenue", negotiated as they shared a cab in New York. This stated that Asimov was required to insist that Clarke was the best science fiction writer in the world (reserving second-best for himself), while Clarke was required to insist that Asimov was the best science writer in the world (reserving second-best for himself). Thus, the dedication in Clarke's book Report on Planet Three (1972) reads: "In accordance with the terms of the Clarke–Asimov treaty, the second-best science writer dedicates this book to the second-best science-fiction writer."

<https://en.wikipedia.org/wiki/Isaac_Asimov#Other_authors>

He was both a science and science fiction writer. Check out "View From a Height" for example. An excellent book.

https://en.wikipedia.org/wiki/View_from_a_Height

He wrote a book about jokes and how to tell them. Quite good.