I have ClamX AV 2.0.1 running happily on three Macs all running Snow Leopard so the problem is not a SL incompatibility but something else.
However, when I went to the ClamX AV 2.0 beta
download site I found the following:
Sometimes, ClamXav will crash when you attempt to launch it. It's an intermittent problem and I would have preferred to hold off until I could fix it, but Apple have somewhat twisted my arm by releasing Snow Leopard ahead of their publicised schedule.