This is complete garbage, even worse than the EM=gravity stuff.
Just consider quarks vs electrons. They have different masses, but the same closed volume (?). It doesn't make any sense.
In fact, I think it would've been enough to stop reading after this
"
The Spacetime Model was also published on November
30th , 2006, on 31 different web sites. It is also referenced on many
sites like Google and Google Books, Yahoo, DMOZ... More than
100 000 internet Users have read it."
Or maybe just after reading he has a patent on it??