Impossible to say at this point.
Maybe Coyoteman will be able to get a look at the papers and share some insights.
I was never convinced by the explanation for radiocarbon dating problems in Great Lakes region posited by that early paper.
A subsequent article in the Mammoth Trumpet seems to be pretty convincing. This is: Update: Article Questioning Radiocarbon-dating Accuracy Draws Fire from Scientists.
The real meat of the article is Brief Comments on "Terrestrial Evidence of a Nuclear Catastrophe in Paleoindian Times," by Richard B. Firestone and William Topping, written by John R. Southon and R. E. Taylor. Firestone has a response following, but I think I would follow Southon and Taylor in this one. I don't know Southon, but Taylor has been at this for many years and is not known for going off on wild goose chases.
All of this is reinforced by the most recent article (Goodyear et al. 2007).
There still may be some problem with some radiocarbon dating in the Great Lakes region, but this article may hold the key to understanding just what that problem is.
The meteor or some other ET strike at about 12,900 years ago seems to be a good explanation for a lot of things.
I think these folks may be on the right track--they have a lot of data, and that's always a good start!
I believe there’s some old topics about RC data from coral, somewhere around here; some study (or perhaps it was more than one, I’m too lazy to check right now, long hard night at the office) regarding the RC spikes recorded in coral are cited in the book (I think, again, lazy, tired). I’ll look for FR links and post them in the next reply (so it doesn’t frog up the “my comments” screen for you.