I have a sneaking suspicion that it's a honeypot. Just a hunch.
Buyers slightly less, considering that the sellers might be cops (which is also the case on a non-honeypot site), or because the PGP-keys of the sellers might be fake (for MITM).
But considering that feds generally seem to target sellers, I don't think the usefulness of this as a honeypot would be huge. But it's definitely possible, especially given that the feds have the source code and all.