How do those who abandon Torah praise a Rasha?
Orchos Tzadikim (Sha'ar ha'Chanifus DH ha'Sheni): This is even if Ploni does not justify the Rasha's evil deeds, just he says Stam 'he is a good person.' Had Ploni not abandoned Torah, he would not praise one who transgresses it.
Mesilas Yesharim (Perek 9): Those who praise a Rasha a do not rebuke him to his face, they abandon Torah and let it be profaned. Those who guard Torah seek to strengthen it. They will contest [Resha'im], and cannot hold back and be silent.
Malbim #1: They envy the success of the Rasha and praise his deeds.
Malbim #2: This refers to above - when there is rebellion, a Rasha rules over the nation. Ozevei Torah praise his deeds, that he conducts with extortion and plunder.
Why will Shomerei Torah confront them?
Malbim #1: Shomerei Torah understand that their deeds are evil, and later they will be punished. They contest those who praise a Rasha.
Malbim #2: When there is rebellion, and a Rasha rules, Shomerei Torah make war with the Rasha and his supporters.
Our verse says to confront Resha'im in this world. "Al Tischar ba'Mre'im" (24:19) forbids this!
Refer to 24:19:2:1-4.
