How does Coffin's status as an abolitionist affect his portrayal of Garner's story and his overall purpose in the text?

According to a different source, this question refers to the text "Margaret Garner: Defying the Fugitive Slave Act" by Levi Coffin.

In this text, we learn about a woman names Margaret Garner who was a slave in Kentucky, but managed to escape. Upon being recaptured, she killed two of her children, preferring death to allowing them to become slaves.

Coffin's narrative shows that he is an abolitionist, and that he is inclined to support the decision of Garner. He describes her story as a heroic and painful one, and argues that only people who have experienced such level of sorrow are able to imagine the pain that Margaret had to endure. The purpose of the text is to show how unimaginable slavery is, and how it can lead people to commit the most desperate acts.