That stuff is great! It foams excessively because it is very highly carbonated, almost to the point of over-carbed. I would say it is probably intentional, otherwise the QC dept at Green flash really missed something.
I got around that by using a large glass, giving the bottle a minute to settle before pouring and using the most gentle of pours to get it in the glass. Even with that, I'll occasionally get a towering head that forms after the pour.
It may have to do with the fact that brett and other bacterial strains will ferment out any sugars that are not fully converted in fermentation. Therefore a very careful amount of priming liquid has to be added so that it does not overcarb. Hence also why a lot of sours are bottled in extremely rigid champagne bottles.