IMO, yr options as usual are going to come down to a question of (a) RA and (b) validation. More specifically -
What is/are the criteria for determining the quoted 6-12 Mo?
Will the same criteria permit a shelf-life extension of XMo. by freezing ? (assuming no other criteria come into play)
If the supplier is able to give you a Yes/No answer, problem solved, one way or the other.
If supplier unable to help, i guess you will have to do a shelf-life study yourself if you wish to justify a freezing step. The obvious first query is whether there is any published data to support the idea for yr specific product. if not, looks like you are going to be a trail-blazer. Freezing certainly works for a wide range of food products.