Wow, that's yeast like I never heard of. But yeah, freeze distilling is just as restricted as evaporative, and with a lot of the things you make booze out of, it can leave in some toxic byproducts that stay behind in the still when you evaporate it. Can't remember what they were, though.
I am trying to find a reputable cite for it, but I don't think that fractional freezing is as restrictive as everyone thinks it is.
I seem to remember that it has to do with the wording of it, unless it has been clarified recently. Something about you are removing water from the compound. The law makes it illegal to use those methods to remove alcohol from a compound. Don't quote me on that yet, untill I find a proper source for that argument.
Going to search the interwebz, be right back.