as long as only 2 wheels are driving then I don't see a problem.
A 4wd running as a 2wd has disadvantages as well like kick up at the front and weight issues etc etc etc.
If you ban a 4wd with shafts removed, then you would need to ban all conversions like the DB1 as that's similar. then if you ban conversions would that mean vega centro etc come in to a ban..??
Personally a 2wd is a car that has 2 wheels driven regardless of the drive train.
simple.