"his statement puts a cloud over every dealer that will be exhibiting at the collection."

There is a cloud over all NV chips that are known in drilled and cancelled condition. People having chips repaired is a "Who's Who" in our club. Some of these guys will have sold off some repaired chips to un-knowing dealers.
If I was buying this type of chip at the convention, from a friend, or on ebay I would make the seller sign a WRITTEN statement saying the chip had not been repaired in any way.
1,000's of these chips have been repaired.

I would not make the above statements without being sure of what I am talking about.