Experts are human but it is their responsibility to not get bored in an important presentation regardless of the presenter. That responsibility means the fault is assigned to them and not the presenter.
I agree with your last paragraph but after any bad event you could point at the presenter and say "I didn't consume the information they were providing - therefore blame them not me"
I agree with your last paragraph but after any bad event you could point at the presenter and say "I didn't consume the information they were providing - therefore blame them not me"