To the PHP parser, it is all one and the same. There
isn’t WordPress core code and theme code. There is merely
the resulting product, which parses as one code entity.
Oh please. This is like saying anything compiled in GCC is automatically GPLed.
There is a specific exception to this in the gpl. Actually I'm pretty sure he's even being too lax in his explanation of what gpl requires. If you distribute the theme (or any gpl connected code) you must make the source available, and anyone who gets the theme can also distribute it all they want.
It is PHP, you don't have much choice in making the source available :)
But if you meant that any visitor to your site had the right to get the source code, then the answer is no - that is not how how the GPL works, and you would need the AGPL for that.
