Theorists are most at home with subject matter they deem to be credible (therefore well-referenced or grounded), and that can be measured (quantified or qualified) in some way.
They may want to be reassured the trainer delivering the topic is knowledgeable enough too.
Theorists will expect to be given links to sources, and other references they can follow-up, and they may well do their own research to check out the substance of the matter after-the-event.
Theorists like to work through things in a logical and rational process. Favouring objectivity and analysis over vague assertions or emotive pitches, Theorists can be visibly uncomfortable with the subjective or ambiguous (aka ‘woolly’) assertions of others.
Where an emotive argument (unsupported by evidence, or theory, coming from the heart) gains any traction within the group, the Theorist may well feel the need to intervene and reassert the need for “reason”, or indeed challenge the very basis of the emotive position.
If their needs are not catered to and their concerns heard, the Theorist can quickly become frustrated. They may openly question the validity or credibility of the content, or challenge the authority of the trainer, either in their ability to deliver the topic, or contain the group.