TV debates: broadcasters will 'empty chair' leaders who refuse to take
The definition of metaphor suggests the expression empty chair is offered as a metaphor:
1 A figure of speech in which a word or phrase is applied to an object
or action to which it is not literally applicable:
In the expression Chairing the Member of William Hogarth's famous cartoon (1755), sitting a victorious politician in an chair could be a literal application of the word, even though it seems to extend the phrase into a metaphorical realm of celebration and honor. The author of this recent article reinforces his metaphorical intent by using apostrophes to suggest the literal 'empty chair' is making a metaphorical point along the lines of:
TV debates: broadcasters will disgrace leaders who refuse to take
We can debate the exact word or phrase that should be used to define the verb phrase empty chair, because it is an idiomatic one-off expression in a complex context, but empty chair seems to point to something that is beyond the chair itself.
Evidence of this metaphorical intent is found in the fact that the journalists would not even need to place an empty chair on the stage to make their point. Of course, putting an empty chair on the stage would empower the imagery, but the moderator of the debates could simply use the verbal neologism to reveal the politician's absence, and the point will have been made quite explicitly:
Tonight we have empty chaired Mr. Politician, who has refused to
participate in our debate forum. We believe he should participate, and
his absence speaks volumes to us. Exactly where his empty chair is
tonight may be one of the questions our debaters discuss.
Since the word chair already has several similar metaphorical applications, this extension of the word's meaning seems quite straightforward:
2.0 The person in charge of a meeting or of an organization (used as a neutral alternative to chairman or chairwoman):
2.1 The post of a chairperson:
3.0 A professorship:
1.0 Act as chairperson of or preside over (an organization, meeting, or public event):
2.0 British Carry (someone) aloft in a chair or in a sitting position to celebrate a victory:
Chair is already a metonym for a position of power and influence, so empty chair is easily turned into a metonym of abdicated power or influence.