You're spot on there. 6x9 should say "23". I've just taken a closer look and it looks like this is actually an old "22" that has been opened up to 6x9. Bought this years ago and never used it much so didn't notice. I can confirm that it works great for 6x9 so if anyone would like it, since it's apparently a modified holder, feel free to make an offer. When I used it, it was on a 6x9 RB graflex Series B which it worked perfectly with. If anyone would like this for that camera, this might be an opportunity to grab one for a steal.
Thanks Old-N-Feeble for pointing out the discrepancy. You've likely saved me some headache.