I have no idea what the max load is for the table, but that much weight isn't going to damage it or anything. It will increase machine wear, and will slow the machine down a LOT trying to accelerate and decelerate that much mass.
May I ask why the giant rotary table? I haven't found any job a Taig can do that can't be handled quite well by a little Sherline rotary stage. Unlike the rest of the flimsy crap Sherline turns out, those tables are robust, accurate, and indestructable.
Also seen them made from planetary gear boxes and a size 23 motor, but they only weigh a few pounds as well.