Suspension is a tool that can be used for many purposes, and one that has been explored by numerous cultures. No culture can "patent" suspension and ask others not to be involved with it. As such, the real question would be, is suspension a cultural misappropriation?Suspension itself -- the physical act of hooks through flesh suspending a body -- has very little cultural meaning. The meaning comes from the ritual and philosophies surrounding it. We can use suspension, but it is our job to come up with our own meaning. As most of us are neither Native American nor Hindu, we can not reasonably understand the nuances of their rituals, and by attempting to replicate them we produce at best a shallow copy that insults everyone involved.
It should be noted that while the above is what most people feel, there are others who point out that cultures are constantly borrowing from each other. They feel that as long as we respect the cultures we appropriate from, that we have every right to assimilate their rituals.