It kind of does if you half the volume. If you end up with the hypothetical gas filled half of a giraffe then it's less mass than if you end up with the meat filled half.
Unless you were only trying to convey volume to begin with then yes it doesn't make a difference.
No part, thats why I said hypothetical. But it's the only way to make sense of the claim that volume Vs mass is an issue.
Hopefully we're not imagining halving the bounding box around the giraffe including the air