If Apple continues to resist, the FBI will simply take the source code and signing keys and hand them over to some contractor to do the work. Is that better? Apple's source code and signing keys in the FBI's hands?
It would be better to push the FBI into that position, yes. Make them steal that property at gun point, literally. Force them to show up at Apple HQ, with SWAT teams, threatening to murder innocent, unarmed engineers in the streets. Make sure every news source available is there to witness and broadcast it live.
Why force it? To drop all pretext of what this really is, and reveal the US Government's actions as being that of the fascist monster it has become. After all, we've got the US military directly, intentionally spying on everything Americans do electronically. We're probably two or three steps or 'events' away from our first Caesar attempting to take permanent executive power. It's going to get a lot worse yet, just look how far they've come in a mere 15 years in their power grab. It's better to just stop pretending, here and now, regarding what's really happening.
It would be the Tiananmen Square for privacy in America.