I'm neither a lawyer nor a US citizen. All I can go by is what I can read, so take it for what it's worth.
I have not read the details of this "Custom Care" program. I did some searching and found a number of New Holland "Purchased Protection Plan" extended warranty variants, but no actual contract. The longest one I found was 5 years. It included considerable detail as to what exactly is and is not covered. (eg: "ENGINE: All intemal lubricated parts that are captured between the valve cover and oil pan, cylinder block, cylinder head, head gasket, ...")
Damage caused by "unsuitable" lubricants is not covered. No mention is made of brand names.
Google tells me that the Magnusson-Moss Act applies to any written warranty -- base warranty or extended warranty -- on a consumer product. I did find some very specific definitions of what New Holland considers to be "Severe Service", which by their definition takes it beyond consumer use. (eg: "Any agricultural tractor that is used in a scraper, earth moving, other commercial, or non-agricultural application, for which the owner receives compensation.") So in those cases, the Act might not apply.
Another thought: is it possible that it is the NH brand lubricants themselves that are warranted? Proving that NH lubricants were installed and changed as required would make sense in that case.