Most vegans I know choose that lifestyle for environmental reasons- livestock farming is very damaging to our environment. Others choose it for health (and they are not useful in this particular discussion), or they choose it because they don't want to hurt the fuzzies.
Now vinyl, being a plastic, is made from petrochemicals, like most other plastics. Petrochemical mining ranks as one of the most environmentally damaging industries. It displaces entire ecosystems, and of course, there's the ever present hazard of oil spills, etc.
Does anyone else find this ironic?