As Snowden, Manning, Assange and now the guy behind Lavabit are demonstrating, there is always a choice.
Hushmail could easily have just shutdown.
For lavabit for all appearances did not have access to any information the government wanted and was not ordered to hand anything over. It seems like they were probably ordered to implement a method for the government to gain access to future communications. They choose to close up shop rather then implement this access and lie to their customers about the security of the service.
HushMail strongly suggested that when given a court order and the targeted user was using the client-side Java applet, that Hushmail sent a backdoored applet. That technically could be detecting by checking hashes, but in practice...
It's an open question whether companies can be forced to build backdoor, but that sure looks like what happened to Hushmail and Lavabits.
(just noting that I'm the author of this more than 5 year old story).
> can be forced to build backdoor,
It seems like they have the option of shutting down as an alternative to implementing a backdoor and lying to their customers about the level of security. If you know of examples of business forced to stay open and the owners forced to continue to work at a company for the purpose of government investigation I would be interested in learning more.
You _always_ have a choice.
And the fact that even Hushmail said that they could be forced to serve malformed Java applets to targets.
EDIT: Not defending Hushmail here, but at least they have some warnings about the risks.