Its intentional language. Lawyerspeak, if you like.
Not all talks at a conference are serious; some are humorous, some are meta-commentary on problems in the field, etc. If you say you are cancelling the talk because it's not scientific or not relevant to the field, the aggrieved party can complain about those other talks. In reality it was cancelled for all of the above reasons, but the one that is most inarguable is that they are not being hostile to a minority that attends the conference.
Not all talks at a conference are serious; some are humorous, some are meta-commentary on problems in the field, etc. If you say you are cancelling the talk because it's not scientific or not relevant to the field, the aggrieved party can complain about those other talks. In reality it was cancelled for all of the above reasons, but the one that is most inarguable is that they are not being hostile to a minority that attends the conference.