You are entitled to belittle the speech as 'nauseating, unedifying and dishonest' if you like lucky but it is your opinion, not a fact, something which is often misunderstood. And as for 'no one can believe' (still a sweeping statement) that too is not correct.
I won't even comment of the risible comment that we should try to oust the Saudis. What on earth gives us the divine right to interfere, unless we believe that we have 'god on our side'?
Cameron is PM. He has a mandate to govern and, to be frank, if he achieves what he set out in his speech I will be delighted. If he doesn't then the electorate will have their opportunity in 2016 to vote in Jeremy et al and he can gave his chance to do things his way then.
That's democracy.