Ben, in my opinion, because the coin can't be verified by PCI, I would have to assume that it could be a counterfeit slab and listed as a MS70 to sell to unknowing customers. The coin dealer also seems to have questions and assumed it was not graded correctly, placing it accordingly. If I had run across it at a low price, I too may have purchased it and then broke it out and submitted it to one of the leading TPG.
Quoting @Conder101 history: "In Sept of 2001 the company was sold to Leslie Slade and a major change was made to the labels. The green border was abandoned and a broad gold border was introduced for the problem free coins. The red border for problem coins was retained but it too changed over to a wide solid red border. The coins now had a 9 digit serial number and the grading got even worse. In March of 2002 the company was sold yet again, this time to Brian Beardsley. This time there were no changes to the slabs, but the red bordered slabs were discontinued and now both problem free and problem coins were put in the gold border labeled slabs but with no mention of any problems. Needless to say, by now people were avoiding PCI slabs like the plague."
NGC they would never know it was in the holder as it would be cracked out first. You can only do PCGS for crossover to NGC.