That just means that yes, that feed contains GMO and that they are not able to tell you how much but they are trying to word it so it sounds happy and healthy anyway -- its just marketing copy with little real information.
Unless what you buy (of any food product) says specifically that is 100% non GMO or 100% organic then it contains GMO. Even "certified organic" could potentially have some GMO because a product only needs to be 95% organic to be USDA certified organic and that 5% could (but does not always) contain GMOs.
If you really want non GMO I would look for a soy-free, organic feed. If it says 100% organic or is labeled non GMO then you are really in the clear. If it doesn't then it is probably has no or very little GMO/
http://gmo-awareness.com/2011/05/05/is-organic-always-gmo-free/
That's exactly the thought that went through my head when I read, "It’s important to remember that all grain is technically genetically-modified, as simple plant breeding is a form of genetic modification."....that's a line of spin-doctoring if I ever heard one.
There are several non-gmo, non-soy feeds out there. They tend to be mashes/dusty. If you find it's not all getting eaten, you can moisten it. I ferment mine, but that's a whole other kettle of fish.
I think Azure is totally GMO free and I know H&H (micobe feeds) is non-gmo, non-soy. There are others.