I didn't go to the details about this one. But for every serious theory in science, there is a number of others that explain the same phenomena, ranging from just alternative to plain crackpot.
Ultimately, what is considered the 'true' theory as a working hypothesis is the one that passes Occam's razor. It seems that this LET theory has to invoke existance of this aether and is hence less simple than the more widespread theory without the need for this additional concept of aether.
Actually, the whole discussion on the existance of this aether could only be made scientific by performing an experiment where the outcome predicted by the LET theory differs from the one predicted by common theory. If such experiment is not possible, the difference between the theories is only in the realm of philosophy or even semantics.