I'm not sure about the A300 but I know several of the larger Boeing products have a threshold speed where the anti-skid system no longer works. It is a low speed somewhere around 10-15 knots (or maybe lower, fam schools were a long time ago). Anyway, if they were trying to make the turn they may have been below the speed and applied brakes. I really don't think the weight of the airplane would affect the actual operation of the a/s system. The system looks at wheel speed and will dump the pressure at impending lock-up whether the tire had a side-load on it (turning) or not. With a/s off or not operating due to parameter affects then a turn can cause a wheel to stop. Then again you may have seen some scrubbing, but that usually doesn't produce all that much smoke.