Even if she was a friend, she's also a politician, and her insertion makes it political.
Kelly wasn't much better though. He didn't once acknowledge the family was offended by what Trump said, which they were, and their feelings are all that really matters.
Then he told a story about the congresswoman to smear her, a story that was apparently incorrect.
And Trumps actions are just as inexcusable, not in his comments to the family, but in the lead up, and then his response after. He said the congresswoman lied, and claimed to have proof. That was, of course, incorrect. The mistake of the congresswoman was in telling the story, not the story itself. She told the truth on that front, and it was confirmed by the family.