It reads to me like there's a distinction between ice and snow. Like the snow isn't considered part of the ice or isn't able to be measured as part of the ice until some compaction has happened, and the "snow" layer might be hundreds of years worth of snow. That's the only way I can resolve the definitions with the statements, and I'm hoping someone can more authoritatively describe the paradox because I'm feeling unsatisfied.
there is also a distincion between the coastal ice sheets and the continental interior ice and snow cap.
the apparent paradox is caused by misrepresentative interpretation of a report, by the author of the article.
the coastal ice shelf and continental interior are two distinct physical systems.
isostatic rebound is a confound to the measurement of snow/ice accumulation when change of altitude is corelated to snow deposition.