Yes, Christians should come out strongly (boldly) against groups that do evil in Christ's name..
First, thank you for bringing this to my attention.
Second, there is provision for speaking boldly to rebuke, exhort, and convince. Not only to speak, but to do so boldly. To preach the Word!
2 Timothy 3:13-17, 4:1-2
But evil men and impostors will grow worse and worse, deceiving and being deceived. 14) But you must continue in the things which you have learned and been assured of, knowing from whom you have learned them, 15) and that from childhood you have known the Holy Scriptures, which are able to make you wise for salvation through faith which is in Christ Jesus. 16) All Scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness, 17) that the man of God may be complete, thoroughly equipped for every good work.
4:1 I charge you therefore before God and the Lord Jesus Christ, who will judge the living and the dead at His appearing and His kingdom: 2) Preach the word! Be ready in season and out of season. Convince, rebuke, exhort, with all longsuffering and teaching.
And for me, that utterance may be given to me, that I may open my mouth boldly to make known the mystery of the gospel, 20) for which I am an ambassador in chains; that in it I may speak boldly, as I ought to speak.
It appears, from the article you’ve referenced and what I found doing follow-up research, that Joseph Koney is a false teacher. It seems that this is a case where we are to speak boldly, to convince, rebuke, reproof and correct.