The four-time Ladbrokes World Hurdle winner has been on the sidelines since December 2012 but is nearing a return to action in the Cleeve Hurdle at Cheltenham later this month.
Trainer Paul Nicholls has flown to the Caribbean to discuss riding plans with Stewart and told The Times that the situation is "not as straightforward as people seem to think."
Ruby Walsh and Tony McCoy are the only two jockeys to have ridden the 11 year old since the Hennessy Gold Cup in 2008 but both riders have commitments elsewhere.
"This is not just any horse," Nicholls told the newspaper. "Ruby knows him inside out and if he was available right through, we'd be mad not to have him but he works for Willie Mullins now, so he can't commit and neither can AP."
Daryl Jacob is the new number one at the Ditcheat stable but Nicholls revealed that he is not guaranteed to come in for the ride.
"We will have other runners in the World Hurdle and, as Daryl has been very successful on both Zarkandar and Celestial Halo, he might ride one of them," he added.
The answer to the question may soon be resolved but there are no such problems for Big Buck's with Nicholls pleased with how his stable star's preparation.
"He's done lots of graft and Rose [Loxton], who rides him every day, says he feels no different to two years ago."