I have read your questions, and personally I have
to say that NO, it does not seem wrong.

If you have ever collected anything for any 
length of time, you may have gone to a show like
AX, or any collectable. The dealers get to 
these shows several hours before the public. Once 
your booth is set up, you can go shopping. Dealers 
buy from other dealers all the time, it isn't 
unfair. Many dealers in other collectibles shop at 
shows specifically to sell on ebay or websites.
In some collectable shows, every dealer is 
shopping at each other's booths until the doors 
open. Why would it be different for cel dealers?  
 
If you put a price on your item at a show, and a 
dealer buys it before the doors open, then great. 
You got your profit and you don't care what they 
do with the item. The idea that they are reselling 
it would be a given.

In this case, it seems that the public even had a 
chance at the cel before the dealer bought it.
So he was taking a chance when he bought it later 
in the day that the price was as high as the 
market allowed. I don't see the harm done, and I 
don't see any reason to question the integrity of 
yet another dealer because of a cel bought for 
resale. 

I can't think of a single collectable market where 
doing something as common as reselling an item 
bought from another dealer would be 'wrong'. I 
think many people on this forum don't realize the 
business involved in secondary market collectables 
is always just as we see here. It always involves 
buying from someone and selling to someone else! 
When the items are never straight from the 
wholesaler, you have a totally different set of 
rules, and this is no acception. Nichibei didn't 
do anything wrong if they indeed did buy the cel 
for resale. This is how the collectable business 
works.