I'm sure you already see the contradiction here, but salt is hypertonic - it draws water out of tissue and into blood vessels, increasing blood pressure.
Exercise increases perfusion. Any noticeable effect would take years, but increased perfusion leads to increased pressure.
Perhaps she drinks too much water?
There are vasoconstrictors, but those are for serious cases where patients cannot alleviate symptoms with lifestyle choices, either because their vasculature simply won't maintain adequate pressure or because the discipline isn't there. However, plenty of pharmaceutical companies, doctors, and other healthcare practitioners would be fine prescribing vasoconstrictors off the bat, so if she wants a drug it shouldn't be hard to find someone happy to make a buck insodoing.
Anyways, I wouldn't be worried about acro yoga with someone who has chronic hypotension. I would be focused on the hypotension.