@Ituri I'm a little confused by these different sources and information streams. As Neil just pointed out, the first source (the Arabian Sand Cat plan) states that ~10 years ago the North American population was a mix of pure Arabian and Arabian-Pakistani hybrids, with no African. Then the second source doesn't say anything about Hawk Creek/Columbus's cats being African; it does say they are "unrepresented in the US" then in the next paragraph mentions that their cats have produced 20+ cubs sent all over the country?
Columbus is listed in ZTL as having African (Saharan) Sand Cat, as is Hawk Creek; on the notes for Columbus it says "import from Chad" and that this was per an email to ZTL staff. I can't find anything online confirming that, though.
Worth noting that nearly all Sand Cat entries originated from what seems to have been an email to ZTL admin. I noticed this was the case for a few other cat species also - and the Reticulated Giraffe entries.