I read that a few years ago. Have a butcher's at http://denverseminary.edu/resources/news-and-articles/the-bible-unearthed/
Yep, as I thought, the main problem with the article is it is an appeal to what is possible rather than what is possible.
The article also confuses the dating of the events of Genesis with the claimed date of writing the events and is occasionally self contradictory. To pick one low hanging fruit:
Even if the number of Israelites was considerably smaller than 600, 000 warriors, it would be impossible for the Israelites to pass through the desert without a trace (pp. 62-63) [claims The Bible Unearthed]. However, that is exactly what many tribes have done for millennia. The only traces of purely nomadic peoples are group burial sites, religious memorials, and written inscriptions.
So the article claims that nomadic people leave no trace but also claims they leave burial sites, religious memorials and written inscriptions. Which is it? In any case, if the Israelites had been in the wilderness for 40 years, surely some people would have been buried and they weren't exactly shy about building altars - at least not according to the Bible.