Everywhere else there is a distinction between virtual currency and real currency. This line just says "currency". It is quite vaque in that it could say "if the person accepts (Bitcoin) from one person and transmits it(Bitcoin) to another person as part of the acceptance and transfer of...value (that substitutes for currency)." Would that mean that every node on the network transferring bitcoins from one person to another is an "exchanger and a money transmitter"?
I think if it just says "currency", they are referring to the FinCEN definition of currency, which excludes "virtual currency".
Yeah, because "currency" here means US and foreign currency. This is a limitation of 31 USC § 5312 (a)(3). They can not just throw "virtual currency" in there. They really deserve to get slapped for trying.
Ok, that makes things more clear.
But what is meant by "value that substitutes for currency"?
Yeah, I focused in on the "value that substitutes for currency" too. I think that was intentionally included to give themselves broad interpretation. I think context is the key. FinCEN deals with finance related items. Precious metals can be used to finance buying things, so that would qualify as "value that substitutes for currency" IMO.
What's most interesting though is that virtual currencies themselves might
eventually be used to finance buying things (if they became popular enough); at that point they would also qualify as "value that substitutes for currency" so an exchange that transacted no fiat, but only well established crypto-currencies might also then be targeted.
They basically want to regulate exchange of currencies; and currencies, by definition, become currency when a large number of people accept them as such.