I'm convinced a 250llbs AJ would have been stopped tonight, late on. His issue is the gas tank. More weight, being slower and tiring earlier is not the solution...
Even if 260 Ibs Joshua hits Usyk clean , it will have no effect. AJ is a feather fisted Heavyweight and does not have the power of a George Foreman or Lennox Lewis. Weight doesn't give you any Punching Power.