I didn't say that. I only said that using the hardware capabilities to sample from compressed textures isn't problematic from a legal point of view, since the vendor already payed the license fees. The usage of the libtxc_dxtn is a totally different issue.
Not true. IIRC, the s3tc license must be purchased for each combination of driver/hardware/OS. I guess ATI has a license for Catalyst/RadeonHD/Linux.