[@AlternateMan]The Radiation would realistically harm you without a shadow of the doubt if it compromised your cell structure, and the integrity. 

While you could hurt the bio-organism invading... The X are very adaptable. It would be unwise for all parties involved, and would lead to a far more painful death than it would be to assimilated and lose your sense of consciousness. If anything, that would be the most painful death you could endure in a effort to save someone. XD