Yeah you won't get an answer on this from anyone directly involved with Sketchup, whatever they say could be viewed as official policy.
My reading of it is if you aren't using if for commercial gain then the free version is ok. ie: you draw up some plans to work out your space, unless you sell those plans to someone there is no commercial gain. But there are many and varied legal loopholes and strangleholds tied up with all of that.
Sketchup does grant non profit licenses, so if you feel you need to you can contact them directly.