It would be better for startups in general if it was customary to open-source your solution if you shut down.
The cost of entry on the market for a SaaS application is so low now, that companies start to ask more and more such kind of insurance.
For some other services, code in escrow could also be a good idea, but when not open sourced from the start, closed source code is often hard to bring back to life as an open source project. Sometimes it works well, for example with Blender.
Indefero is a code hosting/project management software: http://www.indefero.net
Unless they're just removing a competitor, but if that's the case they could always violate the custom.
I was talking with a potential client this morning about how he used to us Drop.io and built some systems based on it in lieu of the API calls he needed then Facebook acquired them.
It may be the case that the Facebook purchase in this case was about more than talent, but if every startup is only buying time until their big exit a general distrust amongst users may be the result.