"Both were shot by left wing loons." Are you suggesting that "second amendment remedies" are only available to right wing loons?

You're partly right. "According to data from the Anti-Defamation League, at least 45 police officers have been killed by domestic extremists since 2001. Of these, 10 were killed by leftwing extremists, 34 by rightwing extremists, and one by homegrown Islamist extremists." 

https://www.theguardian.com/world/2017/may/15/sovereign-citizens-rightwing-terrorism-hate-us-government