She understands that touching either of the twins or Austin would hurt her game. If She uses her HOH to get one of them out then the other two will come gunning for her. She can't have their blood on her hands. That's what Johnny Mac and Steve are there for. Vanessa is all about loyalty and she has been loyal to her group this whole game while still trying to keep herself safe week to week. Unlike most of the people in that house this year, she is playing the game. I personally hope she wins it all.