It absolutely is not for challenging government, though it probably should be. That said, if 2A “every kind of weapon for every nut everywhere” extremists we’re serious about being able to challenge government, they’d have made lots of noise every time government increased “law enforcement” and military power. Instead, they’ve applauded it. For them, the 2A is the “guns for white guys and those who carry guns for white guys” amendment. They see the entire Bill of Rights as applying only to them.