There is certainly no legal objection and on the face of it your colleague sounds suitable, but those on the spot must always be the best judge of that.
In general I confess I would be cautious about making such a choice because the chair does have a great deal of influence on the development of a group, however often we say that that the chair has no special powers.
It might be difficult for anyone who has spent a working life among professionals to make the transition to leading the governing body and to have the right sort of relationship with your own headteacher. But there are such exceptional peopl and you may have found one.
A lot depends on how strong your team is, how able it is to establish and maintain its accountability role and to keep its ears and eyes attuned to parent and community feelings. It needs to be strong enough to ensure that a chair with the necessary time and skills does not get relied on too much. Even the best governing body finds it an effort to keep up with everything and avoid leaving important choices to someone able and willing to make them. You may have to work harder to maintain that sort of hold on your strategic role than you would with another chair, because it is so tempting to have someone knowledgeable and experienced who can save you so much groundwork.
I hope you will all talk openly about this choice and ask these questions. It will be a very good mark for your colleague if he respects you for raising this issue. I hope you have indeed found a treasure and will flourish under his wise leadership.