But Shelley is in despair. Ozy wanted people to look at his huge kingdom and despair at how mighty he was and they weren't. From the Christian tradition this king Ozy got what he deserved. This is the same Christian tradition that looks at Saddam's fall and laughs (I'm not implying any religious stuff like Islam and Christianity; what I mean by "Christian tradition" is the meek shall inherit the earth and all that.)
But, see, Shelley was an atheist and a revolutionary and a protocommunist. He was someone who believed in the individual (he was a Romantic poet after all) and how great the individual is, how great the man can become, what power he can seize, what might he acquire, all in defiance of those who would take it away.
Ozy had all this but lost it because of Time. Time took away Ozy's life and took away the kingdom. All that remains is ruins amongst sand. This breaks the poet's heart. Shelley is in despair that no matter how great you become you still die and what was you -- making a huge impact in your time -- fades away.
The Christian tradition says no matter how great you become in life you still die. Shelley is raging against this.
This is a clear case of knowing about the poet's beliefs and politics before saying what a poem means. If this poem is applied to Saddam, it would actually be LAMENTING his fall.
Of course there is some similarity to certian Deposed Desert Despots.