Unless he is boosting it... which is all too common in the DIY field right now. *shrugs
We are speculating here... Cam hasn't posted anything since OP in October and it was a thread-surrection which we are all responding to.
If the Driver/Sub is being boosted at the tuning frequency, then a protective HPF is usually advised. Assuming the box and port tune are appropriate for the Driver, this might not actually be necessary.
On the other hand, if the box and port are pushing extremes, and/or the Driver is being boosted near its limits...
I believe "dog's lunch" is the phrase you like to use sometimes.
Without Cam chiming in... all of this is pretty pointless, though.