To delight in the truth means to love the things of God. The bible says that we should not take part in the same things as those who love evil. We should not go where they go, act like they act, love the things that they love.
Yet we are still to love them.
We are not called to ignore sin, but we are called not to enjoy it.
Sin hurts. It hurts those who sin, those who are the recipient of wrong acts and it hurts God.
We are not to love sin because of all that sin causes, but we are to love the sinner and point them to the One who can save them from all of their sins.