I doubt we'll know an answer to that for sure. Offers come in many ways. From what I have seen on the videos, and I am sure most posters here saw the same thing, he does not look like he is currently at the caliber of a major school like Tennessee. So I suspect the offer was something other than an immediate full scholarship offer.
Coaches sometimes offer a kid a scholarship contingent on attending a prep school first, or redshirting the first year as a walkon, then earning the scholarship the next year. And sometimes offers are contingent on whether another player leaves early or another recruit fails to qualify. We'll probably never know what the real circumstances are with Cooper.