I wouldn't advise toughened glass for a table top, whatever the thickness.
T. glass is ok for bending loads (as those on a table top), as long as the surface remains intact. But it is prone to "explode" (indeed it will, in thousands of small bits) if the surface is nicked by any hard object with sharp edges falling on it - like some big jars for.
If this wasn't a low table, a plain, thicker glass plate, say 10mm thick, would be safer. For 23 years my dinner table had such a top, 1200x800mm, mostly unsupported. I no longer have it only because I gave it away when we moved 20 years ago.
But for a low table with as little support as the one in the picture, there is at least the risk of a child sitting on it. I have seen it happen, with nasty results. In this case the safest solution would be, I think, a glass laminate, better yet a laminate with tempered glass.
Pretty expensive though, and more prone to show any waving of the glass due to the tempering process. Also, due to the process requirements, it is impossible to get a perfect, clean edge with this solution.
Incidentally, I worked for many years in the glass industry as technical manager of a number of different processing facilities.
