We reached out to ARM to get confirmation on this statement, and received the following response to our question.
ARM has since deleted the post and seemingly unconfirmed that this ARM CPU is in the Nintendo Switch. It is yet to be seen whether this was merely a social media manager error linking unconfirmed rumors, or rather a post that was not yet ready for public consumption. If I personally had to guess, it would be the former. None the less, this is an interesting bit of information.