Similar Problem
I've had a similar problem with my frozen Malbec juice bucket. This is a product from Chile. The day after getting the bucket home, the heavy foaming started. I had drilled a hole in the top, put in a rubber washer, and put in an air-lock. It was filled with foaming wine. I decided to move the must into one of my own 6 gallon fermenters, but realized it would do the same thing in mine as well, so I split the must between two 6 gallon fermenters. This solution handled the foaming.
I also have a 6 gallon bucket of Carmenere. It behaved just fine, with slower fermentation.
The starting SG when I got the buckets home was 1.085. After 6 days, the SG on the malbec is about 1.004 while that of the Carmenare is 1.015.
I plan to add a bit of nutrient to the Carmenre to help it finish, but do not plan to add any to the Malbec.
I added MLF and oak to both yesterday.
It's nice to have the smell of fermenting yeasts in the cellar again.