A normal employer with a normal-world mindset. This is their competitive advantage and they're keeping it for themselves - even though they didn't (in his reading) buy the original code he wrote.

Sad, but a fact of life if you deal with businesses.

if a charting library was their only competitive advantage such that they'd worry if it was opensourced, i'd start looking for another job soon...

and dinosaurs will die

"Employer" is not quite so simple. Organizations are multilayered and complex.

In some cases, your whole department (i.e., bosses and bosses' bosses) could be in open support of this project, but the legal department could shut it down.

Hell, the CEO could be even in support of it, but still be overridden by the legal dept for a bunch of valid reasons.

And not only that, they could benefit from it immensely - by adding a 'sponsored by' link on the project pages.