This is pretty crazy speculation on the reasons for the ‘silence’ imho.
It is, and yet a few times I admit have thought of similar things. But the Bush family has been close to the Saudis for many years, and he was acting in deference to them ever since 9/11 —soon after, his speech to the nation calling Islam a ‘religion of peace’. Was there some kind of ‘blackmail’ then? As President, he could inform them that we would massively retaliate.