"Gravitational waves can't exist in one- or two-dimensional space. So Stojkovic and Mureika have reasoned that the Laser Interferometer Space Antenna (LISA), a planned international gravitational observatory, should not detect any gravitational waves emanating from the lower-dimensional epochs of the early universe."
Only if there are no alternative explanations for the data. If this turned out to be the only viable explanation, then this theory will stand, at least pending more data that might strengthen it or show it to be in error.
So if it doesn't their theory is proven correct?