True, but:
1) Shakespeare seems to be deliberately taking advantage of this, especially if, like Branagh does, we take an anti-war slant - the Agincourt battle-scene seems to emphasise the horrors of war. I also wonder whether Shakespeare, by having the case for France proposed by the Archbishop, who has other motives for going to war, is subverting the idea of a 'righteous war'.
2) The Branagh version seems to imply that Henry is aware of the hollowness of his claim. When the Archbishop explains the problems concerning Salique, he finishes and declares that, this being clear (and all laugh), then Henry is the rightful king of France. The fact that the council is laughing at this joke implies some sort of knowledge of hollowness.
But, hey, I'm no Shakespeare expert