Perhaps because the type (63) 68 was select fire.
http://world.guns.ru/assault/as48-e.htm
But if they could have been modified before import they might have been a sweet variant to have as I read it has a bolt hold open, can be fed by stripper clips and is a detachable mag.
Also they made 1 million of them...
Random note - the Chinese AKs are ALSO Type 56's. Guess they picked that up from the US with the WW2 M1/M1/M1/M!1 deal
I recall an article I read years ago where Peter Kokalis was told by people in the Chinese arsenal system that some 6 million were made. Who knows? The rifle was considered a failure by the PLA because of ongoing quality & accuracy problems. In I980,