It sounds like this claim is too vague and causes you to not be able to choose what it is actually claiming. Does the claim insinuate that water is unhealthy and will make you gain weight? You've shown in your sources that can't be the case. Does it insinuate that water has weight to it so consuming it would inherently make you heavier, ok sure, but the source they provided states there is a difference between water weight and actual weight gain. The claim is much too vague, and you answered it the best you could in my humble opinion.