He is certainly an accomplished (and fit!) sailor - I am sure that he could afford a bigger, more conventional boat for voyaging in, but he does not care to.
There is a very long thread about him on the Boat Design Forum - Why I'm Following Sven Yrvind
Re sailing in a small boat, maybe Sven would be better off with a boat more like this one in the video link below - she is only 4 metres long, but this lad crossed the Atlantic in her in 29 days.