N&G is correct, that officially you would have to check the rules.
However, I think it poor practice, and would check quietly with the sport's governing body, although the exact relationship between the governing body and local clubs can be very variable.
I think it poor practice because there could be both conflicts of interest and an absence of the usual checks and balances.
However, it can be so difficult to get people to do these jobs now, that it may be that a coach with an interest in keeping the club going is the only person who wants to stand!
If that's the case I would be influenced by how 'important' this club is - a few adults who enjoy getting together is a different kettle of fish from one that trains youngsters and enters them into representative competitions.
I would try to find someone else to stand, and if you can't, suggest that the coach becomes a 'facilitator' rather than a formal chair.
Sometimes, sadly, clubs do fold.