Are backflow preventers for irrigation required to be lead-free if the upstream source is a potable water system?
The interpretation of statutes and laws (which are often deliberately inexact and/or vague) happens in court when an entity protests a citation or complaint, or when the regulatory authority decides or is compelled to deliver an interpretation. Until one of these happens, it is up to you to interpret as well as you can. You should think of it this way: "how would a majority of average right-minded persons interpret this?"

My interpretation (whatever it is worth) is that the device is located on a line that is not "providing water for human consumption"; additionally, the device is specifically designed to prevent water from flowing back towards systems that are "providing water for human consumption". Also, this product is specifically designed for use in irrigation systems...