Surely grounds for excommunication and being black-balled from The Lodge!? 
Check out a movie called The Sin Eater, also known as The Order, with Heath Ledger. Don't pay any attention to the critics; those semi-literates missed all the cultural references.
I think even F-1 fans often fail to realize the high fitness levels drivers possess and the work required to get and stay there in between stints behind the wheel.
Remember David Coulthard's neck? Built like a tree trunk -- a redwoood, at that. It didn't happen on its own.
Nico Rosberg, who was Lewis Hamilton's teammate, and whose own World Drivers' Championship interrupted Hamilton's run of championships for Mercedes, immediately afterwards retired to spend more time with his family. He gave a fascinating description of how he hardly saw his family in the previous year as he worked with his trainer to prepare him to beat Lewis Hamilton, one muscle at a time. I imagine a bicycle racer who wants to win also trains muscle by muscle.
It's not surprising that track racers develop necks bigger than their thighs. The g-forces on a car racer are greater than on a fighter jet pilot, and happens multiple times over a race weekend, whereas the fighter pilot suffers such his top g-forces perhaps a handful of times in an entire career, or never if there are no wars during his career.
I would think that he will be contracted to drive so has no option?
All drivers' contracts forbid bicycling or motorbiking on the public roads, permitting cycling only under the supervision of the driver's trainer because cycling is too valuable a training method to forbid. But Cadillac is a new team and Valtteri Bottas is one of the few available top drivers (ten victories, years at Mercedes, twice runner-up in the World Drivers' Championship) whose experience they need to develop their car. So, while it is unthinkable that even a new team would have overlooked such a standard clause in the contract, Bottas would have had some negotiating clout about a mainly off-road second sport.
Related information from my protege Dakota Franklin, author of the Ruthless to Win set of books: Fernando Alonso, twice world champion, thirty-something victories, universally considered one of the greats, has a clause in his contract with Aston Martin that he won't enter a race where he has unfinished business, the Indy 500, while he drives for them. It seems clout goes only so far.
