Maybe NBC and CBS before them was trying to address something fans here say all the time - we want more in depth commentary from someone who knows what they are talking about. In 1990 Peggy Fleming hadn't competed in year, Dick Button in decades. And did either ever coach or choreograph? Maybe the producers wanted Bezic because in addition to be a former world level competitor, she was then a top ranked choreographer who could add a different perspective to commentary. And, she was well versed in pairs, not just singles like Dick and Peggy. Having just done Boitano's Olys gold program (as well as Brian O's silver the same year) plus a ton of other skaters, I can see where she'd have some resonance to US audiences.
I'm not saying she was the best choice, and certainly there are others who do a far better job now, but back then, I can see how she might have got the job.