This is absolutely right. When the stomach is full of MAOI´s, the DMT will be completely surounded by it and fully protected. If you take the DMT with the harmala´s, it won´t have the same degree of protection. You shouldn´t wait too long either, because then some harmala´s will already have left the stomach.
It´s also true that taking just a little more harmala´s than strictly needed for MAO inhibition, will give a stronger experience. There is not one sharp line where you suddenly have full MAO inhibition. It´s an area of around 50 grams of caapi, where 40 grams could be just too little to give that full MAO inhibiting effect and leaves you with only very mild DMT effects, 50 grams can cause just enough inhibition to give full blown DMT effects, and 60 grams can give a total protection of all the DMT you take, resulting in an even stronger experience.