This article doesn't explain why he refused what they called
> The order, issued under the Stored Communications Act, required Lavabit to turn over to the F.B.I. retrospective information about one account, widely presumed to be that of Snowden.
Sure, but you can make some reasonable guesses from other available sources, including his own statements. But his motivation is not really the issue we were discussing - it was whether the government just up and destroyed Lavabit on a whim. You said "it doesn't change the fact that US killed it since the government wanted to have access to all users' data without any restrictions and warrants." It doesn't change the fact because the fact is not a fact.
However you want to interpret his actions, there's little doubt that Lavabit's grief was entirely self-inflicted.
My point is, since he didn't refuse previous targeted requests from authorities, it's reasonable to assume that this case was somehow different. I.e. for example it was formally targeted, but in practice they demanded more than necessary, or it wasn't technically possible to do what they wanted without compromising others who weren't suspects, or something of that sort. So without knowing his reasoning it's not obvious that it's "his fault" and government didn't want to kill Lavabit originally or government didn't overstep its power to begin with.
> The order, issued under the Stored Communications Act, required Lavabit to turn over to the F.B.I. retrospective information about one account, widely presumed to be that of Snowden.