Yep, sounds plausible to me. Vonda McIntyre's novelization also tells a good story of what might have happened between Spock's funeral and the Enterprise's return to Earth, although you know how much of the fanbase usually is....even novelizations of canon films and TV stories aren't canonical.
Frankly, the only thing that makes The Final Frontier
and Sybok hijacking the Enterprise-A to the center of the galaxy even passably logical is what J.M. Dillard explained in his novelization about how Sybok and his followers modified the ship's warp engines using information from "visions" sent by the entity so they could make the journey.
The novelizations can be a big
help from time to time.