I say good on her for carrying through with the threat!
We've always warned our kids of any consequences and then carried them out.
One of the things that winds me up the most is a badly-behaved child and a parent saying: "I'm going to count to five and then [do whatever]. 1...2....3....4....4 1/4....4 1/2.... 4 3/4....."
Followed by silence that goes on until child gets fed up of whatever it's doing and complies.
Then: "See, now you're behaving you can have a treat."
Though I suspect that this mother-daughter relationship will be somewhat strained for quite a long time....
