I don't want my manager to write code generally speaking. It's a gateway to problems.

I don't mind if they read and try to write something and run it in dev to see how things are going.

But otherwise I find too many "manager writes code" turns into him being the exception to all the rules and ... some of those rules about planning and talking to other devs exist for good reasons. Suddenly they're the exception to everything and breaking things and some folks don't want to call them out or worse they think the managers one off "quick fix" is now a pattern we use and OMG ...

I've worked with some great managers who coded and they did great work and no amount of "hey don't do that" "oh yeah I won't actually stopped them from eventually crossing the line and making bad choices.

Absolute power corrupts absolutely and the same goes with many managers coding.