I can't believe this is new news. I had 9 shots of botox in my left leg in 2015 and it wasn't a new idea then. It was used in a spasticity clinic attached to Epworth Hospital (a big hospital) in Melbourne. The report itself is borderline misleading but I'll settle for it being mashed up by journalists. It's a common thing to use.
Botox can be a useful adjunct for spasticity treatment. It destroys the connection between the neuron and the muscle so if you then exercise to stretch the muscle when the neuron grows back you have a more elongated flexible muscle. It wont work if you don't use the 3-6 month window to stretch the muscle.