This is *not* an open vs. closed source thing. This is a "people attempting to make money off hobbyist emulation" thing (something which there's a depressing amount of lately). NSRT's original intent (I read this in a forum post by Nach) was to convert ROMs to a compressed proprietary format which they would then charge everyone money to use once it caught on. If that's no longer happening, wonderful.
That said, extending headers is still the wrong way. Just look at the title of this thread.