Telling only one side of the truth is a form of a lie.
If you are actively soliciting, and distributing dirt on only one of the parties involved in an election, though it may be the entire truth, you are not being HONEST.
Especially if the information you are releasing was providing to you by a malicious 3rd party State who/which is releasing it to you in the hopes of influencing the election so that a candidate preferable to that 3d state comes into power (Russia).