Riku did NOT accept that they acted like they were dating... he accepted that they were weird and that they were fine with weird.
"Sora," Riku tried, frustrated. WHY did Sora act so hurt about this? And he didn't SAY that dating Sora would be a horrible thing. Sora... Sora was his BEST friend.
Really, the car was not the place to be talking about this.
Riku pulled into one of the parking spots that was marked by a log and stopped the car, getting out promply to get their stuff out of the trunk and leaving the waking of the kids to Sora.