does this mean pfsense whatever release cannot add or modify anything that is on freeBSD HCL it is based on
No, I just said the exact opposite of that. The base OS is FreeBSD 8.3. The dev team has updated some drivers to allow newer hardware to function, notably, as per this thread, the Intel em, igb, and ix drivers.
Once 2.2 drops the base OS will be changing to FreeBSD 10, bringing with it updated drivers across the board.