They should not have final say over a candidate based on personality or communications skills. They should be a source of input (i.e. this guy is an asshole, because he was very rude to the guy who helped him scheduled his callback interview, or perhaps more importantly to inject some company-wide context into what can turn into a group-specific analysis) but it's the technical people who know what kind of communication goes on in a technical team, and thus it's the technical people who should evaluate a candidate on that characteristic. Yes, this requires trusting your technical people and investing them with a greater responsibility to understand the dynamics of their work group. That's a good thing.
