Does there need to be only one method? Perhaps, just perhaps, both methods have their own individual merits and are worthwhile in their own right. Is that at all possible? Does the fact that Botox works necessarily negate the possibility that Facial Yoga might work? It's nice to have a choice. And speaking for myself, I would prefer to have a soothing, relaxed facial massage than have Botox needles freezing my face into a fixed grimace (Have you seen Joan Rivers lately?). That's just my opinion though.
It's not that, but that they're options espousing totally opposite solutions to the problem of looking aged.
One is don't move anything, stay expressionless and no wrinkles - Botox
The other is move everything, use your facial expressions and no wrinkles - Face Yoga
They can't both be right.