I work for an OEM in body design and I have been involved in designing countermeasures for bodies that have failed the FMVSS 216 test. Number 3 has laid it out very clearly as to why it would be very difficult to offer T-tops, not just in the Camaro but any modern day car. Watch the video he posted,
http://www.bing.com/videos/search?q=...87168CEDA7B384 and pay attention to the placement of the ram. It contacts the the corner joint where the header, A-pillar and roof rail connect and it runs rearward along the roof rail back to the B-pillar. On a T-top roof that is going to be the weak point. There are no exotic materials that can make up for that amount of lost structure.