We say Sage mode because Jiraiya himself called it that when he fought Nagato.
Are you really gonna type Rikudo Sage mode every single time you mention it?
Just call it Naruto's SS mode. I mean its pretty much a copy of Super Saiyan with some symbols drawn on his skin.
9 tails Chakra mode is the official name the wiki is going by. I'm just gonna call it Naruto's super mode.