A brave activist and a talented writer, she had weathered the hardships of political exile. Since 1994, however, she has been embroiled in scandals that have included at least one inexplicably remunerative black economic empowerment transaction.

Latterly, as speaker, she has been decried as a Luthuli House stooge who has helped the ANC parliamentary caucus bury the Nkandla scandal and endorsed the violent ejection of unruly opposition MPs.

But on Monday, Mbete announced that the motion of no confidence against President Jacob Zuma would be voted upon by secret ballot. By this single step, she was transformed – at least in her acolytes’ eyes — into an exponent of principled politics. On her own account, she had undertaken impartial consideration of all relevant legal, constitutional and political factors and concluded MPs should be free “to follow the dictates of personal conscience” behind a veil of secrecy.

Unfortunately, there are no real grounds for supposing that Mbete had discovered a constitutional backbone last weekend.

Luthuli House was confident that Zuma could survive a secret ballot. Since the incumbent faction presumably has access to various surveillance technologies, there would have been no need to install miniature cameras in voting booths or to bug MPs’ phones. Combined with whips’ knowledge about MPs, this would be quite sufficient to establish the likely ballot outcomes.

The danger for the ANC was not that Zuma would be evicted, but rather that the identities of those voting against him would become publicly known. This would have fuelled a post-vote witch-hunt, led to internal disciplinary processes and ultimately resulted in a Constitutional Court case that the ANC would undoubtedly have lost.

We should note that there has been no groundswell of loyalist anger against Mbete’s purportedly brave stand for constitutional principles: Zuma’s crowd also believe she was just following orders.

There is an alternative explanation that we should consider for Mbete’s uncharacteristic moral rectitude. Perhaps she believes she will become ANC president in December.

Zuma reportedly “dumped” her candidacy in 2016 in favour of that of Nkosazana Dlamini-Zuma. However, so unelectable does the former AU Commission chair appear to be that cynics suggest Zuma had always planned to pull the rug from under his former wife. In her place, he might once have mulled over a further term for himself— in the interests of unity and party electability, of course.

Now, it is the Zuma name that is the problem. And, given that it is “time for a woman”, a third term for our redoubtable ANC president has become doubly unlikely.

What, though, of Mbete? Born in Natal in 1949 — just like Dlamini-Zuma — age would make her a convenient one-term president. She would have to rely on Zuma to assemble a support base for her in December. A week ago, she would have been viewed as the president’s stooge, just another proxy designed to protect Zuma and his cronies from prosecution.

Now, Mbete could be presented as an independent-minded political leader, who refused to capitulate to Zuma’s will. Her reputation, we would be told, was burnished by her principled stand in support of the Constitution and the dignity of Parliament.

• Butler teaches public policy at the University of Cape Town.