2D data availability with Kate commitments

Shouldn’t the block proposer download and verify all the proofs (they don’t have to generate the proofs), not just “run a data availability check” (assuming that means just DAS)? DAS relies on others DASing as well. Attesters have an incentive to DAS a proposal, but not to DAS a pre-proposed blob. I feel like otherwise a block proposer could get trolled into proposing a block where some blobs are only partially available, and thus miss out on attestations.