I quite clearly added the reaction of the truck pin. You are counting the luff load twice. It only appears at the masthead in the form of the halyard tension. It is not connected to the boat in any other way. The ONLY load on the masthead is from the tension in the lines. The luff load is taken 1/2 by the line going to the pin and 1/2 by the line running to the sheave. Each has 50 lbs. Then the 50 lbs in the fall to the deck.

Using your logic we should get 250 lbs load at the masthead: the three lines at 50 lbs each and the luff load at 100. 400 years of Newtonian physics, rewritten.

But I rest my case. I'm sure anyone still following the discussion has reached a conclusion.