I agree with you ladies. I usually just ignore the tantrum (because they are just looking for attention) and try to redirect them to another activity, or give them time to calm down. Then, when they are calm, I ask if they would like to join the group.
The timeouts don't work for the toddlers because they don't stay for long, so i just make sure they are away from the other kids so they don't cause any injuries until they have calmed down.