I don't see how you could consider "heating up" is a metaphor for winding down. I just don't.
Well think of it in terms of boiling something. Just as things are about to come to a boil, htey are heating up. Once boiling begins, there is no further increase in temperature. It'll stay constant at 212 degrees, no matter how long the boil occurs. So just as things are about to come to a boil, they are "heating up" as they aproach the climax, which is shortly followed by the conclusion.
From the persective of the article, the interviewing process is the climax, and thus the boiling point of the story in question.
But the article was written in the perspective of just prior to said climax. Very shortly after the climax, the end occurs.
Don't think of the two metaphors as related. Think of them independently of each otehr. Both are describing the same event in different ways.
Things heating up implies that it will soon be a climactic moment (which happens at the END of a story).
And the thing is, winding down does not imply "slower" or less climactic. An egg timer winds down, but it never heats up.
Both stories are using different metaphors to describe the exact same thing: the approach of the end.
They are just using different metaphors. One describes time, the other describes cooking.
In other wqords, I'm not saying "Heating up" is a metaphor for "winding down" since winding down is ALSO a metaphor.
They are BOTH metaphors used to describe the end of something.