Isn't 6 confirmation an outdated method? In most cases, as far as I know, 3 confirmation is a safe bet and some websites even use something like confidence factor where they calculate via some methods the probability of double spend.
There is a rule of thumb saying that it is extremely unlikely for a chain reorg to be 6 blocks deep. The six blocks rule of thumb comes from the math in the white paper and an analysis in a very old post here somewhere.
Has it ever been 5 block deep? 4 block deep? And what will happen if chain reorg will be 6 blocks deep? Will the 6 block criteria just grow or can it turn into a huge problem?