Something about that Arabic alphabet just looks wrong to me. Even as a kid, I never liked the look of it; it looked somehow inherently wicked. Is that visceral reaction wrong . . . ?
Don’t worry about their language; beware their religion instead.
Not all Arabs or people that use Arabic are Muslims. Our Christian brothers in Egypt, Lebanon, Syria, Iraq, etc. use Arabic. Aramaic, the language of Christ, looks like a mix of Arabic and Hebrew.
I wonder whether Tolkien used Arabic as part of his inspiration for pure evil.