Yes, a double negative. That doesn’t make it easy. lets try to make it clearer:
Genuine practices of meditation which come from the Christian East and from the great non-Christian religions, which prove attractive to the man of today who is divided and disoriented, can constitute a suitable means of helping the person who prays to come before God with an interior peace, even in the midst of external pressures.
From Merriam-Webster:
Definition of superstition
1 a :a belief or practice resulting from ignorance, fear of the unknown, trust in magic or chance, or a false conception of causation
b :an irrational abject attitude of mind toward the supernatural, nature, or God resulting from superstition
2 :a notion maintained despite evidence to the contrary
This fear that certain poses open one to the demonic by their very nature seems to me to fit this definition.
The account in the article could be a confluence of all sorts of things.
Here is my story. Lets go back to 1975 when I was a college student smoking pot, drinking beer or whatever, chasing girls, you name it. I took a yoga class mostly because of the girls in it. But through the stretches, the breathing, the release of tension, perhaps toxins and all that is entailed in a good class I began to ask deeper questions. You can do that because as you are stretching, holding a pose, your mind can think of all sorts of things. I slowly began to reflect on who I am. What life is all about. And in the physical peace that comes from the practice I would also get a taste of mental peace. I gave up all those vices and went back to Mass. Yoga has been a gift for me, a way to more fully engage my body in my spirituality. It is very incarnational, sacramental. If God’s spirit is to dwell within us, we need to do all that we can to honor this body and treat it like a temple. I do my yoga in the name of Christ. We don’t need to change the name of the practice, just the name of whom we do it in.