The headline is really wrong. Mozilla is shipping compiled and executable code to us. Now, if its Perl, I can confidently say I'm shipping Perl code to you.
Their source contains the actual Rust code and it's part of the build process. Distribution build maintainers will compile that rust code when making their packages. I run Gentoo, so that process happens when I upgrade Firefox.
Well, "shipping" could mean shipping the source too.
Why am I being down voted? Is my comment not relevant at all to the topic? Why not just ignore my comment or reply with the advice?