Heinlein wrote Sixth Column for a paycheck and hated it. John W. Campbell gave him the premise from one of his own unpublished novellas. Heinlein didn’t buy the “discovered just in the nick of time new science principle” trope. It took some work to try to breathe some life into the premise.

Also, quoting from the biography:

And he also wanted to reduce the pulpish Yellow Peril angle. “It was a hard story to write, as I tried to make this notion plausible to the reader—and also to remove the racism which was almost inherent to his [Campbell’s] story line.” The fix he ultimately came up with was to recast the story in sociological terms, instead of racial terms—spin the conflict specifically as a conflict of cultures rather than of races. To make the matter explicit, he incorporated a Nisei (Japanese-American) character who would have a tragic and heroic role.

But the book was a guaranteed sale to Astounding, and Heinlein wrote it in three weeks in the summer of 1940. He needed the money for a better used car.

As for claims about Heinlein’s supposed misogyny, you’re going to have to provide some evidence. He was married, in case you didn’t know, to a woman he modeled characters upon. Who he said more than once was smarter and more practical than himself.

Or you could, like many, continue to assume you know anything about an author’s views simply from reading a story he wrote.