The researchers didn't state their own conclusions were erroneous, or they wouldn't have submitted their paper for publication. Other scientists did, including NASA colleagues. (Note that Zwally and his colleagues are competent scientists and this falls well within the normal range of scientific discussion.)

As for your claim that ICESat "collected data for a full five years", this is false.

http://nsidc.org/data/icesat/laser_op_periods.html