Yes, that would be short for "He tried to touch you?" So there is a verb which comes after which is understood and without that information from the previous sentence, it would have been incomplete. I am not sure if grammatically speaking that question is considered complete. We sometimes cut speech and yet is that considered a short version, a colloquialism or an error? You could as easily have said "He tried?"
I put "He tried it?" which was accepted. I keep thinking the sentence was Él lo intentó. I also keep wondering: What happened to "lo"?
Way back in the stone age, we were taught that the 3rd person singular pronouns were él/ella/lo; and Usted (formal, singular), always capitalized, and ustedes (informal, plural) were 2nd person (except for having the same conjugational form as ellos/as) along with tú. So what happened to "lo"?