It isn't specifically prohibited. I can see why it might be; it does provide an advantage over the standard auto-aim. But it doesn't seem to fit in any of the categories of prohibited modifications:
3D-Skins with Display of Modules and Crew Positions
Removal of trees, leaves and bushes or change transparency
"Lens scope" modification that removes tree leaves and alters bush transparency around the aiming reticle.
Script automated use of manually activated equipment. I.E. Automatic use of Manual Fire Extinguisher
Modified Tracer Display (case-by-case basis)
Free camera
Laser Reticle (red line starting from the gun barrel)
Mini Map modifications that passively provide information to the individual player without the use of active teamwork.
Yes, this behavior is useful. I have never used it before, so I thought that behavior would be considered a bug. If that's the way it is designed then ignore my report. :-)
Scott