Found it here also.
Lists a weight limit of 200 lb, but I'm not really sure that the weight limit applies in this case. The weight limit is more than likely computed based on a load from one direction in which case all of the forces acting on the cleats are in a direction to shear the cleats. The shearing load as you have used it is canceled out by running the line through the cleats in both directions and on opposing sides of the cleats. The only real forces on the cleat as used for the hammock suspension as you have, would be the compressional forces on the cleats and the torsional forces. The latter forces are working in concert, but they are limited by the fictional forces, I seriously doubt that the torsional forces would be sufficient to twist a cleat off. The frictional forces are probably not sufficient for that, the rope would more than likely slip first. Seems that the plastic should be able to handle those forces if it can handle up to 200 lb shearing forces on the cleats.
With all of those cleats, the frictional forces, as you have demonstrated should be sufficient to hold the hammock, but I'm cautious enough that I would again add a slippery half hitch after bringing the rope back through the cleats.
Great idea. I really, really like it. Now if I can find out how much one of those cleats weighs.