It's fairly uncommon for open source software to blacklist components that (attempt to) implement a compatible interface. Usually selecting an appropriate hardware driver is left in the hands of the distribution or administrator.
Yes, and the distributor or administrator is free to rebuild the browser or just set the flag to disable blacklisting. It’s only default behavior that changed.
Yes, it's different. You can build trademark Firefox so long as you do not modify it at all. You cannot build Chrome from the chromium sources — there are components which are not present in the open source repository. It's not just the trademark, unlike Firefox vs Iceweasel.
