Gotta say, I agree with all this.
Re-reading the OP, there was no mention that the co-worker doesn't like her hair texture/curl pattern or its appearance. It sounds like she didn't like the way her hair
acted. The fact that the hair still looks almost the same with the texlaxer seems irrelevant
to me, because you will have changed the way her hair
acts.
So now she will get used to her treated hair and when her shrinkage prone natural hair grows back in, the same old problems will be there (problems she won't have learnt to deal with).
Either that, or she is going to wait until her hair grows 'x' long where she will have to
hope that the weight of it will defeat shrinkage and make it act the way her texlaxed hair acts, even though 'x'-long might need to be, what, mid-back length?
Also, she now has the new issue of two textures to deal with (and trust me, even if they look the 'same' they will not be) and possibly the dryness/porosity issues chemical treatments tend to bring.
I kinda get your theory and your happiness at saving her from the relaxer, and I'm happy that she's happy with the results so far, but someone who after one year (or whatever) of being natural is so frustrated by her hair that she was about to relax doesn't sound like someone who is going to be a long-term transitioner.
I would have discussed anti-humectants, methods to keep hair stretched at night and the pros/cons of regularly wearing extensions since I would not put on someone's head what I wouldn't put on mine, but I guess everyone's different.