Bold Math in Section Titles

From ConTeXt wiki

When a section title is formatted in boldface text, this doesn't automatically typeset embedded math in bold. This is probably a good thing, as many math fonts do not include all characters in boldface, and often authors use boldface to distinguish between different meanings (for instance, scalar and vector variables). However, in some cases, it is desirable to format the math in the section titles in boldface.

Here a very simple example:

\section{Bold $a^2+b^2=c^2$ {\em bla}}
text: not bold $a^2+b^2=c^2$ {\em bla}