People use technical jargon in all kinds of scenarios in which there's no plausible motive for obfuscation, use of jargon isn't evidence of deliberate obfuscation. In this particular case, "break their necks" sounds fairly humane while "cervical dislocation" sounds unpleasantly clinical, so I doubt this particular jargon is intended to obfuscate.

On the other hand, "put it to sleep" is definitely such an obfuscation.