Appeal to truth you mean. The Lucy instance is documented fraud and not just to do with the knee joint. You can say what you like otherwise, it won't erase the fact of that fraud. Period. At the time of the find, the skull was smashed beyond recognition - did'nt stop anyone from making up how she looked intact and passing it on as a fraudulent transitional - just for starters. And it is supportive properly of the point I made. The appeal is to the truth of the fraud. Regardless of any other argument you wish to make.
Christianity is a big thing. Creationism is a little thing, and it has a religious horror of the truth.
Ad hominem
I say the problem is on the creationist side, and here comes evidence for what I'm saying.
addressed and rebuked. As the record stands, it looks as though this guy made the admission and everyone's been backtracking since. Not my problem. I and everyone else I have read has far more problems with Lucy than just the knee and I know of no one making the case on the knee alone, though I would agree it is brought up. The denial now is about as believable as the denials about other frauds. CYA seems to be a whole industry with ya'll. So, I'll leave it at that.
You say this, but then you don't back it up with citations.
Most skulls of any size and age are found crushed by sediment pressure and are jig-saw puzzled back together. This can introduce controversy and confusion but does not constitute fraud. Fraud is a spectacular claim which a real Christian would avoid unless he had some evidence for it. Not being religious myself, I'm in no position to say for sure, but I'll guess that a militant YEC is probably not a good example of a real Christian. YECs reliably exhibit several species of bad behavior that the good citizens (Christians virtually all) of my experience abhor, the utterly reckless flinging of accusations being but one.
The existence of multiple Australopithecine species and specimens thereof found by several people in several places makes it extremely unlikely that every reconstruction is wrong in the same way. I'm aware of no evidence of fraud regarding Lucy and have already provided links dissecting the usual creationist dumb-dumbisms on the Australopithecines.