I think tht user meant arabs lineages not autosomalLol, what a bunch of bullshit. This dumb myth is so widespread.
Levantines have very little European crusader ancestry. They have about as much blood from Niger, Chad, South Sudan as they do from European Crusaders.
The history of African gene flow into Southern Europeans, Levantines, and Jews - PubMed
Previous genetic studies have suggested a history of sub-Saharan African gene flow into some West Eurasian populations after the initial dispersal out of Africa that occurred at least 45,000 years ago. However, there has been no accurate characterization of the proportion of mixture, or of its...pubmed.ncbi.nlm.nih.gov
'' Levantine groups harbor 4%-15% African ancestry with an average mixture date of about 32 generations ago''
32 generations = about 800 years.