Obviously there are terrible acts people can perform (murder, torture etc)
However words can incite people to peform those acts or drive people to suicide. Many leaders of terrorist organisation do not commit acts of terror themselves, but inspire others to do so.
That said, I don't think anything Christopher Biggins said would be put in that category. However we just don't know what was said. Leaving people with no evidence so that they jump to conclusions, or using the incident to promote the programme and get people to tune in, is in itself immoral. Whatever he said, the BB production team are milking it in order to publicise their programme.