I doubt we can satiate greed. Either a politician is honest or he is not.
Whether or not politicians are more or less honest than other people could be the subject of a lengthy discussion, but it isn’t the main point, here.
Reinforcing their temptation to violate the public trust, in the form of allowing them to accept donations from lobbyists is.
In effect, the writer’s saying the public has first call on buying them off, and ought to exercise that right.
Either the moon is made of green cheese or it is not.