If you have a player that is sitting around with nothing to do for the encounter b/c he can't use evil eye, then he's either not being very creative in finding other ways to help the party, is playing a character that is not very well rounded, or both.
No character can cover all bases. This is especially true of lower level characters. If you engage in spells like this that shut down entire attack modes (a lot of spells require evil eye) then you will be seriously affecting people that rely on them. Its all very well saying that they are not being very creative in finding other ways to help the party, but the Scholar is primarily a non combat class who has to be fairly creative to help the party in combat at all, without this kind of thing.
Not to mention that if cheap defensive spells like this proliferate, then avenues will be shut down far faster than players can open them up.