I spoke with the guy that builds the wiring harnesses when I bought mine. He said that disclaimer is on the site because they were concerned about what would happen with the relays and the reduced voltage from DRL - but I tested it myself and it turns out that the DRL voltage is enough to cleanly trigger the relay to the "on" position. All that happens is that you will get full-brightness hi-beams as your DRL.
I didn't want that, so I just used my AEV Pro-Cal to flash my computer to use my factory fog lights as my DRL.