When reading your comment I was surprised that someone was “presenting”. No wanting to sound too cranky, but that should be kept to a minimum. I have run meetings that were about disseminating a fixed block of information, in which I would give someone who was not paying attention a hard time. I do however only do that when I am very certain that what is being presented is relevant to the vast majority of those at the meeting. If it is not highly relevant then it should not be in the meeting. That is the job of a chairperson: guarding the relevance and value of the content of the meeting.

If someone is genuinely not getting any value out of a meeting then they have my permission and their own obligation to go be truly productive elsewhere.