The restricted transfer port was Steyr's attempt to restrict the power of the rifle to less than 12FPE, even when fitted with a power adjuster. You still get more than enough shots to shoot a comp.
This was done rather than fit any AT devices which others wanted them to do. I think Steyr should be applauded for this as you still get a rifle that you can set the power on without having to "Mod" it like a lot of other PCP's.
Having said that, BASC's interpretation of the legislation says that once a rifle goes over 12FPE it becomes Section 1 "Capable" anyway. How do other manufacturers of PCP's now power down rifles that have gone over power, or do they replace them ?