Looking in ephinany-browser, the reason it is coming up correctly is because it's initial page is set to
file:///usr/share/ubuntu-artwork/home/locales/index-%l.html
Firefox doesn't support setting this as a homepage, which is probably why the alternatives system is used in the first place.
Looking in ephinany-browser, the reason it is coming up correctly is because it's initial page is set to
file:// /usr/share/ ubuntu- artwork/ home/locales/ index-% l.html
Firefox doesn't support setting this as a homepage, which is probably why the alternatives system is used in the first place.