Tol-in-Gaurhoth XVII: The Saga Continues to Continue quite Continuously

[Shelob]

But then, why not kill Glirdan or Kath (who also saw some attraction in the theory)? Why not indeed? Hmmm ...

The most obvious reason "why not", and the one you're "Hmmm" seems to favour, would be that they were wolves. Doesn't that seem overly perfect and nice? It's far more likely that if this were an attempt to frame Valier/Form/Wayne then killing Glirdan or Kath would also draw attention to a real wolf. It seems to me that with this kill they'd either want to follow through on hints/suspicions of a gifted villager or kill someone who would get us looking in the wrong direction.

Assuming that that's the case we can probably rule out that the wolves thought they'd found a gifted in Aiwendil. Which means they're Probably* trying to send us in the wrong direction. If they chose the Valier/Form/Wyane trio to cast suspicion on then clearly killing someone who seemed to agree with it would be a good way to cast said suspicion. However if they also killed someone who had a real wolf in their suspicions, or someone with whom a real wolf has alligned themselves killing that person would also bring into the spotlight the real wolf they're associated with. Aiwendil was probably just misfortunate enough to be in a position where the wolves could kill him without putting any of their number in danger. The safest kill which still accomplished something.

(*It's a matter of the Bluff/Double Bluff, personally I doubt it's worth it for them to put any of their number in danger so early but since it's possible we shouldn't discount it completely)