That's not necessarily a bad argument, but the theoretical basis of the criminal burden of proof is that the kind of consequences resulting from criminal conviction are different than mere property (which is routinely at issue in civil cases).

So, the principle on which the existing distinction is based really doesn't support it being applied to forfeiture actions.

And, while there might be a good argument for changing the principle underlying the distinction, I don't see a clear reason for applying specifically the beyond a reasonable doubt standard to forfeiture (or even a higher standard that would apply in any other civil claim.)