What you're mistaking is that intention-manifestation works perfectly and exactly as expected inside a subjectively perceived reality
. A subjective perspective necessarily requires intention-manifestation, because the viewed reality is, by definition, the manifestation of your intentions.
Framed in this way, SR and I-M are painfully indisputable, as they're just flat-out self-evident propositions. Anything convenient is supportive, because that's the way it works.
I can't grow wings and fly because I don't believe I can. That's completely in accord with SR and I-M. If you believed you could, then you'd be able to. That doesn't mean other people
would believe it happened, even if they were "present". This is because other people are extensions of yourself, and thus see only what you expect them to see. It's entirely possible that you believe that they see your wings.
It's almost fortunate that SR believers aren't generally philosophical heavyweights. (And those that are also aren't stupid.) Every one of them still believes they're human beings, rather than space whales floating across a temporal web stretched across galaxies.