Comets can’t explain weird ‘alien megastructure’ star after all (newscientist.com)

There's no remaining explanation consistent with this new data, according to the author.

    “The comet-family idea was reasonably put forth as the best
    of the proposals, even while acknowledging that they all
    were a poor lot,” he says. “But now we have a refutation of
    the idea, and indeed, of all published ideas.”

Any astronomers care to comment on what rules out these explanations:

1) Planetary nebula, with patchy bits

2) Inherent star variability

?