I think that the issue comes from the fact that "Daemonology (Sanctic)" is specified within psyker entries of the Eldar (Craftworlds and Arlequins) Codices, as the basic rules already allow every army to use both sides of Daemonology (with two exceptions for Grey Knights and Daemons who have access to only one side of it without perils on non-6 doubles).
According to loki619, this could mean that Eldars would not peril on non-6 doubles too. But there is nothing into the rules telling (or even opening the door of interpretation to) that.
We could however argue about the possibility for Eldars to use Malefic Daemonology powers : the basic rules state that "Unless otherwise stated, all Psykers, other than those belonging to the Tyranids Faction, can generate powers from the Daemonology discipline. The Daemonology discipline has not one, but two different sets of powers, one labelled 'Sanctic' and one labelled 'Malefic'. Each time a Psyker generates a power from the Daemonology discipline he can choose to generate it from either the Sanctic or Malefic set of powers. For the purposes of Psychic Focus, the Sanctic and Malefic sets of powers are different psychic disciplines."
RAW speaking, the "Daemonology (Sanctic)" discipline specified for psykers of the Eldar Codices is just redundant (as it is already allowed by the rules for Sanctic and Malefic).
Fluffy speaking, making Eldars conjure Daemons is not a heresy. It's worse than that : something that could make the Universe crumble
What could be arguable is the following : would the specification of "Daemonology (Sanctic)" on a psyker entry match the "unless otherwise stated" of the rules ?
In that case, it would be some kind of (welcomed, according to me) restriction for the Eldar psykers. But it has nothing to do with the exceptions for perils, which are linked to a specific Codex (Grey Knights) or a trait (Daemon).