between the alcohol and honey - the stick is pretty much sterilised each time it's used, I would think.
Yeasts are alcohol tolearant - well some are. So regularly use of the stick would probably kill off anything but the more alcohol tolearant yeasts.
It's not necessarily as daft an idea as it sounds
And if you stored it in a jar of honey that would keep it sterile.
Might also be interesting to see what happened with just the honey and yeast, no water.
Would you get a thick alcoholic honey ?
Probably not
The other thing is that you probably have more than one strain of yeast in your wild mead.
Over the years the lower alcohol tolerant yeasts would die off and the mead would gradually get stronger as the more alcohol tolerant ones survived and flourished and stuck to the stick.
It's a bit like people who say that our ancestors only used salt to cure their meat, so why should we use nitrates.
In reality, over time people would graduate towards salt from a particular mine or area because it did a better job. And that would be the salts naturally rich in nitrates.
So over the years the stirring stick might well end up making stronger mead
More than enough reason to keep it in the family.
Or not
But it does make sense.
Our ancestors weren't idiots and many long standing traditions have a practical core to them.
Did you take the specific gravity of the starting mix ?
be interesting to know how much alcohol you get.