Well, it won't kill you and likely won't even make you sick, but the thing is, cake breaks down after a month in the freezer. After two months it is more noticable and so on. Some folks are less sensitive to the changes than others are but there is actually a measurable deterioration. Likely with cake mix cakes it is less because of all of the chemical preservatives in them. Fruit cake has the longest life, about 6 months in the freezer. I have customers and friends swear the cake was every bit as good - from scratch cakes. I use butter and cream in my cakes and icing. Personally I wouldn't want to eat them. Doesn't matter to me how they were boxed or wrapped.
The larger the cake, the better it holds up to freezing.
This is an old tradition, not necessarily a good one, in my opinion, haha. I am in favour of a fresh cake for the first anniversary or the first child's christening - which this cake is also traditionally saved for.
Hugs Squirrely Cakes