Cranmer and Peter Carrell have both written about what an opportune moment this is - during ARCIC III, an ecumenical gathering between Anglicans and Catholics - for the Roman Catholic Church to excommunicate Mugabe.
At the moment, it seems everything in the Communion is about ecclesiology and homosexuality. The case with Mugabe and Kunonga is no exception - previously Anglican bishop of Harare, now excommunicated, but vying for control of the Anglican Church of Zimbabwe with Mugabe's support. Kunonga initially claimed that the Church of Zimbabwe was ravaged by homosexuality, and because of this, purported to withdraw the diocese of Harare from the Anglican Church of Zimbabwe, creating his own church. It was widely speculated that this was a nonsense claim, to rationalize moving the diocese in a grasp for power. He is now strongly supported by Mugabe. There has been a murder and a rape, death threats, much intimidation, and many put out of their churches. Mugabe has ordered that in the diocese of Harare, church services are to be held under order by Kunonga. Home church services are being held in defiance of the order, even though police are enforcing Mugabe's and Kunonga's wishes. The situation has recently escalated.
This would indeed be a good time for Rome to excommunicate Mugabe.