Your script reads incredibly well. Do you edit yourself, or use spellcheck and then copy and paste? Either way great job. I think that any direction you want to go with writing new plots into the Halo story is awesome. Even as crazy as they could possibly get. As long as it does not affect established storylines.
I feel that people do not just stumble across this forum. The people who come here, even if they do not join, must have a great respect for the Halo universe. I may be too trusting, but I doubt that any of them would have any desire to steal or plagiarize your intellectual property.
Go team Sigma!