hi!
Tested it a bit. So, it works so far!
Some questions though:
1. SelectGrow outputs vertex and face selection together. Maybe you should set an output selector (verts/faces)?
2. There is something wrong about the algorythm. To reproduce:
a) Import a the mokey head model from Blender (.obj),
b) Select some vertex/faces (doesn't matter) on the top of its head.
c) Use grow selection and you will see that the monkey's eyes will stay unselected!
What could that be?