Yes, a good summary of the situation. I imagine he will become silverbacked shortly as he establishes his dominance over three willing females.
Zaire certainly is not too old to have more babies- some Howletts females still breed into their forties. However, Zaire has only bred once, in 1987 (female Kamili, now at Belfast) which is probably due to poor group dynamic and succession of males they have had at London since then. So after so many years(22) of no reproduction,there must be a big question mark about her fertility now...