Lavabit's problem was that they actually had access to the data, so they were capable of providing records and they didn't provide them. Then pen/trace laws require cloud email providers to provide this data to LE upon authorized request, and case law does not really support payment for hours expended to implement any data collection solution.
Demanding the SSL key in order to plug in their own packet capture (and we must presume appropriate filtering, yeah right) was a -- 'if you can't give us realtime feeds, we can get one ourself'.
So overall I think there are a lot of stark differences between Lavabit and Apple's case, thankfully. Apple is on much stronger legal footing. The corollary is iCloud and Apple has long since provided everything they had there, and there was no question they were required to do it.
Despite the differences in the two cases, it makes sense that Lavabit would want to help defend Apple's position.
There's only so much time they and their staff have to do research, so members of an industry and their legal representatives can contribute if the judges are on the fence or just looking for arguments.
Page 16 is the Thirteenth Amendment argument.