White belt showed up with a blue belt

Just to preface, I'm not hating on this guy. He really is a nice guy and this does not affect me, as I'll just go about my everyday business but thought it would make for an interesting discussion. So we have a guy that has been training for at least 3 years, off and on. A buddy of mine says it's at least 6 years but I'm not sure. I believe he previously had 2 stripes on his white belt. He's a big guy. Say 6'4, 230-240lbs. Hasn't made much progress over the years. Very little technique and lots of brute strength. He's been away for a couple months and showed up today with a blue belt. Said he got it while training out of state. "Tested and passed with flying colors". My question is, as an instructor at our home gym where he primarily trains, do you honor this? Do you tell him to wear his white belt? I kinda chatted with my instructor during a rest and he wasn't too hip on him showing up with a blue belt when he's clearly not.