There are dozens of medicinal cannabinoids in cannabis. They reduce inflammation, help healing, protect nerves, improve oxygenation, treat pain, and so on. I don't think we can assume the cannabis only "made it more difficult" on herself, although I get what you're saying.

Anyhow, that said, I don't think she should be penalized. Cannabis is medicine. Performance enhancing? Maybe, if you consider tylenol to be performance enhancing. Cannabis is awesome, but using it shouldn't be considered cheating!