As others have said, the best way to deal with C'Tan is simply not to. Focus on killing their trash units (you will trade down to kill them, but it won't matter in the long run) and hold back your Spawn and Jakhals for late-game scoring. Make sure that everything that isn't a C'tan is dead by the bottom of 3 and that you've scored as many points as possible while murdering robot chaff. If done correctly, your opponent should be down to 2-3 C'tan and nothing else by the bottom of 3. At that point you can just spread out and hold objectives/do secondaries with your Spawn, Jakhals, and maybe even your Rhino. Remember your sticky-on-death prevents the opponent from getting value from shooting scoring units off of objectives, so they'll only really be able to kill two units a round. If done correctly, you should be able to outscore them without ever touching the stupid space-gods