And if you read Heinlein’s corpus more broadly, you will find those who roll their eyes at the space marines, principally the officers of the Interplanetary Patrol, one of whom takes a very dim view of Matt Dodson’s request to transfer there.
Gosh I loved Space Cadet. Read it over and over again at school.
Heinlein is not in any way uncritical of the characters and scenarios he creates.