So you're basically saying that a meeting could fail to create value because an employee made mistakes in the meeting as he could not handle the stress. The correct way to solve this for everyone involved is to reduce the amount of stress everyone is under in a meeting and to create an environment conducive to problem solving. This isn't really that hard, a well motivated employee whose rewards and goals align with the company will try his best to create value as it helps him the most as well. If an employee is very bad at meetings, he could also be asked to express his ideas beforehand to someone he feels comfortable with and then that person could help him express his idea in the meeting.

The solution of hiring only people who can shout the loudest and brute force their ideas through in combative meetings is not a solution that will create value over the long term. If someone is breaking down in your meeting the problem is the meeting, not the person. Fix the meeting. Even people capable of taking stress is meetings will still perform better if that stress is removed.

EDIT: You also shouldn't be making snap judgements in a meeting that will affect the future of the company in the market. If there is a lot of tension in the meeting and the outcome is unclear, postpone the issue a short while until people can work out the issues better. If someone notices that there was a mistake in a previous meeting, work through the mistake in the next meeting and change direction ASAP. And obviously, don't fire anyone for this...