A political decoy is a person employed to impersonate a politician, to draw attention away from the real person or to take risks on that person's behalf. This can also apply to military figures, or civilians impersonated for political or espionage purposes.
A political decoy is used to help get more people to vote for a certain politician.
This statement is definitely incorrect because the passage states that political decoys are used to draw attention away from politicians or to take risks on behalf of the politician. They're not used to gain more voters.