AFAIK nobody has yet been killed for burning a flag. Many people have been killed for just being of the same nationality as someone who was seen as insulting Islam, let alone burning a Koran. Your slippery slope fails to establish it's contingencies as factual and therefore qualifies as an abuse of the 'transitivity of implication' . (It's neither that sloped nor that slippery in other words, )
Since nobody likes my car analogy how about a person who uncaringly lets their vicious dog kill their child? By your logic you would justifiably destroy the dog but let the irresponsible parent off scot free. Aren't our soldiers entitled to the same concern for their safety that we expect parents to give to their children?