Oh noes! Let me goes out nao un' uprootz all mai bebbies!
Lets me pickets teh florist!! Burn all teh lilliez! *waves burning pitch fork*
I really want to say it just sounds like more fear-of-life-and-living propaganda! In the site's absence of any referencing of scientific or legitimate sources of information, and with no personal experience of such effects, I find it hard to give it any credence.
However searching online for 'lily poisoning of cats' turns up all sorts of vet's warnings. Who knows how these 'facts' get started, but maybe there's enough volume of observation to cause concern to some. I've never experienced it though and I certainly won't be tossing all my lilies if I ever get another cat. A person's capacity for accurate risk perception can be easily warped with fear campaigns - and we live in spoon-fed cultures that hardly encourage us to live realistically and comfortably with risk! Common sense out the window; over-reactive panic is the norm.
That's my political soapbox for the day
And I love cats.