I doubt it would cause any damage. The force of road impacts will often greatly exceed the bike weight, so even though the hanging force is being applied in the opposite direction, it should have no effect. The closeness of the pairs of the 36 spokes and the pressure within the tyre will both act to keep the rim conforming to shape.
One proviso I'd make is to lower the bike weight onto the hook gently, not drop it into place. Also, if there is any visible point where the rim is joined, (rims are made from continous strip), avoid hanging it at that point.
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