They have had a most unaccountable amnesia if this is true, having progressed from knowing something about it to knowing nothing about it. I consider this to be extremely unlikely.
I file such protests alongside of the disclaimer a militant liberal of my acquaintance used to warm up with about how Main-Street conservative his values really are. When he got to his real politics, he was just this side of Stalin.
That they have some knowledge and understanding of what it is you are talking about but have rejected it for the truth.
Nobody who thinks Java Man is a gibbon (and announces its scientific name as Pithecanthecus erectus), or Stephen Jay Gould authored a "hopeful monster" theory, or believes in 2004 or later that there are (God help us!) "no transitional forms" has the tiniest semblance of a clue. OK, there's ignorance and militant ignorance, but it's still ignorance.
Some of the frustration of Christians is trying to have discourse with a "evolutionist" that has not bothered to delve into the creation aspect of it. Maybe they are in evolutionary horror of it.
There isn't much to learn in creationism, but such literature as it has is quite familiar to the science defenders on these threads. The situation is not symmetrical at all. You're having a fun game switching the labels before parroting the arguments, the usual creationist echolalia, but it only shows the usual disregard for the truth.
I've read and debunked I don't know how many articles by Gish, Morris, Sarfati, Behe, Dembski, Meyer, etc. When I do so, I always read the article and for at least some time afterward can correctly characterize what it said. A creationist, if he skims a mainstream science article at all, will go through and count the occurrences of "maybe," "probably," "could have," etc. Ten minutes later he knows nothing, nothing, nothing, nothing of its contents.
I don't mean he should have called it Pithecanthropus erectus, either.
The idea that someone was once a genuinely knowledgeable evolutionist, and then somehow switched to creationism, is about as likely as someone who was once a deeply committed Christian bible scholar, who then gives it up and converts to voodoo. It just doesn't happen.