The thing is this law only applies to murders anyway, so you'd already be in massive trouble without this law.
Do you have a source on this? I've currently woken up and am currently trawling the net trying to find something appearing to be an official transcript of the word of the provision, and new stories, at least, are waffling back and forth as to whether it's just killing or, as you say, specifically murder (At least one I've seen so far is saying that killing a first responder
becomes first degree murder, with not mention as to mitigating circumstances -- so a manslaughter or self-defense charge would be upgraded.). The latter case would be pretty much no-issue (well, maybe. Mandatory sentencing in general is a bit scuzzy.) but the former has potential problems. A link to something official would be really nice...
As for what you linked, PTTG, what's your $0.02 on it? Most of what I'm taking away from reading that article is that maybe we should be reigning back the legal system a bit instead of relying on prosecutors to "correctly" inconsistently apply the law.