I think the amount of accessible bitcoin is far less than 16 million. I would go as far as to say the amount is probably half of that. You cannot imagine how many coins have been lost over the years.
It would be great if you can present some data instead of some inaccurate guess. There's a post up there that you can use to filter transaction data, so you can research on your own. Without something like that, your argument that only half of the supply is left can be easily rebuked by saying something along the line of "you cannot imagine how many coins are not lost over the years even if people believe they are".
As this guy makes such substantial claims it would definitely be necessary to see some evidence backing his claims up. I don't think half is lost. From the reports I read the number four million seems to be about right although it is very hard to estimate even for companies with the tools to investigate that question technically.
One big fraction of that amount might be Satoshis coins alone and nobody knows where he or she or they is or are and whether those people are still alive. SCW did file another lawsuit I think but by now nobody believes him anymore.
Anyway, the number is hard to estimate, but more Bitcoins are most likely going to be lost in the future (death, etc), making Bitcoin truly deflationary.