Hey there.
Justin's initial assessment was almost certainly based on two parties' high initial level of enthusiasm (Gran seemed like a good fit for UK and UK seemed like a good fit for Gran). And, on the surface, what's not to like? Despite its struggles in recent years, UK is still in the SEC, and the latter provides a great opportunity for offensive-minded coaches (be they QBC or OC) to challenge themselves against the best defenses in the country, often with a high-paying and surprisingly stable* seat at the table.
The benefits of moving into such a position must be weighed against the risks, however. Fair or not, the OC position at UK has almost certainly gained a reputation for recent turnover. That alone may not speak to much, but if the perception develops that OC is the default fall guy for the football program, many candidates who express an initial interest may have second thoughts when delving deeper (i.e. talking with former staff). While I still think Gran to UK is a very good possibility, I do think Justin may have called this one a bit too quickly.
*In comparison to SEC HC and DC positions