Not only was Geisel virulently anti-Nazi he was a huge opponent of the American isolationist enablers. His cartoons of the time were particularly bitter towards Charles Lindbergh, essentially portraying Lindbergh as a Nazi tool, which he certainly was, if he wasn’t an actual Nazi himself, which is likely.
On the other hand there were no more vile racist caricatures or Japanese people than those by Geisel.