I dont think its right. what about on a very drawy board when we have Axs and the board all the draws miss on something like 6h7hx y z.

Its quite possible he is bluffing here, but its also quite possible we get looked up light since all the obvious draws missed. Calling gets value from bluffs. Raising probably gets looked up by any made hand.

You might be onto something on a very dry board, but then a bluff is a tiny part of his range on a dry board anyway.