The EPA's site has this information:

"Although some blends contain flammable components, all blends that are Acceptable Subject to Use Conditions are nonflammable as blended." (*footnote for Butane)

Freeze 12 was listed as acceptable (with conditions such as fittings, labeling, etc).

Unacceptable:
OZ-12
R-176
HC-12a
DURACOOL-12a
R-405a

The following 18 states ban the use of flammable refrigerants such as HC-12aŽ and DURACOOL 12aŽ in motor vehicle air conditioning, regardless of the original refrigerant: Arkansas, Arizona, Connecticut, Florida, Idaho, Indiana, Iowa, Kansas, Louisiana, Maryland, North Dakota, Oklahoma, Texas, Utah, Virginia, Wisconsin, Washington, and the District of Columbia.

Not trying to argue here...just trying to understand and document so I can take this to my mechanic.