I don’t see why the usual infrared argument doesn’t apply to them or KIC 8462852.
If by infrared argument, you refer to the idea that a dyson swarm should radiate in the infrared, this is probably wrong. This relies on the assumption that the alien civ operates at earth temp of 300K or so. As you reduce that temp down to 3K, the excess radiation diminishes to something indistinguishable to the CMB, so we can’t detect large cold structures that way. For the reasons discussed earlier, non-zero operating temp would only be useful during initial construction phases, whereas near-zero temp is preferred in the long term. The fact that KIC 8462852 has no infrared excess makes it more interesting, not less.
If by infrared argument, you refer to the idea that a dyson swarm should radiate in the infrared, this is probably wrong. This relies on the assumption that the alien civ operates at earth temp of 300K or so. As you reduce that temp down to 3K, the excess radiation diminishes to something indistinguishable to the CMB, so we can’t detect large cold structures that way. For the reasons discussed earlier, non-zero operating temp would only be useful during initial construction phases, whereas near-zero temp is preferred in the long term. The fact that KIC 8462852 has no infrared excess makes it more interesting, not less.