I generally like Planet Money's style, in which the reporter/correspondent will do a majority of the narration, paraphrasing and interjecting when the original speaker isn't saying something particularly notable. Sometimes this is just necessary, interviewees don't always speak in complete and or/concise fashion, especially when doing boilerplate description.
In the example you give, I think the interjection is fine. Healy, the U.S. postal inspector, gives a vague description of Felipe – "a physically little guy" – and the reporter interjects with actual specifics. I don't think the flow would be noticeably better if this was the edited cut:
> HEALY: He's a physically little guy...And not overly muscular
If it's unnatural to include before or after, that's because it's not that relevant to the story in the first place. It's enough to be able to picture that his risk is compounded by a physical disadvantage, we don't need to know his exact dimensions if that data isn't worth bringing up afterward. And if it is that important, the middle of someone else's sentence is the most flow-breaking place you could possibly put it.
Yeah I think this is definitely a style preference. Planet Money (and other featurey shows, like This American Life) often tries to describe the non-aural qualities of the people in their stories, ostensibly to better humanize them. It's not for everyone but I personally find it to make the subject more engaging.
In the example you give, I think the interjection is fine. Healy, the U.S. postal inspector, gives a vague description of Felipe – "a physically little guy" – and the reporter interjects with actual specifics. I don't think the flow would be noticeably better if this was the edited cut:
> HEALY: He's a physically little guy...And not overly muscular
> NPR: Felipe's actually 5-foot-4