No it is not, do your research. Insoluble mercury is a whole different matter. I haven't died yet. And, some have said that dentists are scaring people in order to get them to come in and get them all replaced. The source you posted is similar to those I have read.
Organic mercury is extremely dangerous, yes.
I've said that. Yes, but it still poses a significant health risk. Please also refer to the quote above concerning cadmium. Lead is FAR LESS toxic than mercury, if it wasn t we d all be dead from the lead in the environment from leaded petrol. Flake white is more dangerous than Vermilion because it is organic and contains soluble lead.