I just checked and there is dimethicone in the Urban Decay primer. I think the Sephora girl who told you to never use silicone around your eyes was confused since they sell the Urban Decay primer.
You can build up sensitivity to ingredients over time. I have heard of people who can't use silicone in hair products due to scalp sensitivity so who knows.
__________________
"If you have men who will exclude any of God’s creatures from the shelter of compassion and pity, you will have men who will deal likewise with their fellow men." — St. Francis of Assisi, 1181-1226