Tutu van Furth told the BBC that the Church of England decision "seemed really churlish and hurtful."
The BBC said that because of the church ruling the funeral on Thursday was moved from St. Michael and All Angels Church in the village of Wentnor to an outdoor marquee nearby so Tutu van Furth could preside over it.
Kenyon, who died Sept. 7 at the age of 92, was a long-time friend of Desmond Tutu. The South African anti-apartheid icon died in December, aged 90.
In 2020, Kenyon was one of the first people in the world to get a COVID-19 vaccine, and his matter-of-fact interview with CNN outside a London hospital went viral.
"I hope I don't get the bloody bug now," he said. "There's no point in dying now when I've lived this long, is there?"