That's quite a strange remark coming from an ethicist of any kind. It seems that he's inviting others to believe what suits them most instead of what is right. Yet somehow it doesn't surprise me much given the country he comes from.
And for example, which "incentives" would you consider to stop thinking that animals are capable of suffering? Is feeling better when buying meat a good enough incentive for reconsidering your position?
Caution based on the false or imaginary is not a legitimate haven.
> might cause great suffering
An implausible idea that suggests lack of lucidity and the ability to hold hypoteses in their proper space calls for severe doubts on mental strength.
> which "incentives" would you consider to stop thinking
No sane individual proposes considering thinking the false.
BTW: you have not fixed the title. https://news.ycombinator.com/item?id=50035187