broadens her horizons/possibilities

I guessing that if she wanted to only be a college head coach, she could have been already. If she wants to open avenues into other coaching directions (pro assistant, pro head coach, etc) as well as get exposed to other ideas and knowledge/human networks, this is an excellent move. She does this now and she doesn't get typecast into "women's college coach." And it is also easier to do this now, rather than after having been a college head coach.

She can always return to coaching college basketball, particularly if she does that within 2-4 years especially with her pedigree of having worked for McGraw.