Even
@Maxperson agreed that a branch from a tree would be valid. It was one of the examples he provided, which we ultimately agreed on. We simply disagreed as to whether a stone would be valid.
In any case, as
@GMforPowergamers pointed out, the 25% chance of being off site isn't exactly a big deal. The only thing the object eliminates is a minor inconvenience.
Deny the GM? I AM a GM. I was literally describing how I would run it, and how I believe it should be run, based on RAW (as well as good GMing practices).