I have not watched the video, so I don't think my judgment is worth much, but for a man cussing from the vileness of his heart; to respond in manner of saying that he is a "foul-mouthed hypocrite" is simply telling the truth. Railing is the use of name-calling in a contentious manner, whereas even Jesus called men hypocrites, vipers, whited-sepulchers, etc. In short, I don't think Ken was in any error on that point, but again, I haven't seen the video.
On the other hand, answering "no" to the sin question; I agree with Thomas. Personally, I find it better to say that I repent of my sin, and that's the difference between the believer and the unbeliever; they try to justify their sin instead of grief of their wrongdoing and turn from it.
My question would be why we would desire to have conversation with a drunk man. I likely wouldn't even address him, but rather, I would address anyone else listening.
Them that sin rebuke before all, that others also may fear.
-1Ti 5:20
If the drunken man claimed to be a Christian, then 1Co 5:11 would apply, but if he did not, as Thomas said he was an atheist, then 1Co 5:11 does not apply, so I don't want anyone to jump in and start hammering down too hard on Kenneth, especially since many of us are not out doing what he's doing.
That being said, I should probably look into his videos myself because I have not yet done so.