If Sabine is on a blocking space, can she throw a grenade off onto a non-blocking space?
Why I'd argue no: for this to work you'd have to count spaces from your blocking space to a non-blocking space. Since these spaces are not adjacent you shouldnt be able to count spaces this way.
Why I'd argue yes: Counting spaces says you count the number of movement points a figure would have to use. F.A.Q. v30 says "If a figure or object without mobile occupies a space containing blocking terrain, apply the rules for mobile to that figure or object". From that viewpoint a figure moving off of blocking terrain ignores the terrain, and by extension counting spaces off of blocking terrain should ignore the terrain as well.