What makes you say that? Did the C'tan ever actually register the Tyranids as a threat? As to the Newcrons, they are actually more united now than when they were divided amongst themselves between the C'tan, because they were sects/cultists worshipping/being controlled by the individuals. Now, apparently the Silent King is pulling everyone's strings. There might be individual dissidents, but they are in the minority iirc. Sorry, but tough that you feel that way. I see Tyranid players battling amongst themselves nearly every weekend. If I recall correctly there's even been some fluff battlereports in the WD that was about one being 'tainted' or that it was a 'biological testbed' for a next invasion... and even if there wasn't there ya go, I just fluff aligned it haha.