By the stories, he went to visit both Sagat and Akuma.
Sagat particularly stands out. Since we only get Kage vs Akuma on Kage’s side, and that is a reasonable direction for Ryu’s meditation to go, you can count that as acceptable. But Sagat? You can, and people did, argue that Sagat shouldn’t even be open to what happened in his story. Out of nowhere, a SnH entity taunted and tormented.
So we already have some form of SnH entity taunting and tormenting a non-practitioner, which is followed by Kage’s story saying that it was Kage that did the taunting.
At that point, you’ve already got an entity that arguably isn’t bound to Ryu. Even if it only did it on some spiritual plane, it was able to travel to an arguably completely unconnected person who was in a different country and directly affect that person.
Does Kage even need Ryu now? Does only “Kage” need Ryu? Is Kage an actual sentient entity, or is “Kage” only a persona or mask? If “Kage” is a mask, is it worn by some sentient entity, or did some non-sentient force/entity attain sentience through Ryu? Will Kage continue to exist without Ryu, die without Ryu, or just have the “persona” of “Kage” die while the entity continues to exist?
Can Kage outright possess another person? Remember that the world of Street Fighter has entities like Bison as well as Necalli. It has numerous energies like psycho power, soul power, the SnH… Akuma has the actual ability to turn into Oni; it isn’t just a metaphor or a state of mind. Though this is really a bit of a cheat, as it ultimately comes down to whatever the SF writers want to do, and they can get away with pretty much anything at this point.