I think it is the verbiage that the warranty does not cover their equipment if it is used in a "non temperature controlled environment" (aka outside or a garage that isn't heated and/or cooled). Pretty much all the other treadmill makers have a similar verbiage I believe.

If you're going to run it in a garage you most likely might be on your own if something breaks. Might as well try to find a good condition used treadmill if thats the case honestly.