that maiden song has nothing to do with Predator. it's about the life of a mercenary. Hence the title: "The Mercenary". if they wanted to do a song about the predator they would name it "The Predator". Maiden isn't too big on hiding secrets in their songs.
isn't there a song called "Get to the Choppa" out there by some death metal band?
edit, here it is:
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I like it!! That song rocks!!