The official answer seems to be: CIG trying to get as many people to the Manchester office and he may or may not be unwilling to relocate. That's just my guess though.
GamesIndustry has additional comment from CIG on the matter.
For what it's worth, he's been replaced by Richard Tyrer (director of Squadron 42).
100% agreed. Nobody could be blamed for not wanting to relocate for a job and it's honestly kinda ridiculous in this day and age that they're requiring them to. Remote work works!