So basically the Air Walk glitch is possible with normal controller inputs. I had the idea in my head so went and tried it and found it worked. So turns out the way that Air Walk glitch actually works is that when you are a frame before landing you have the character perform a double jump. This is highly restrictive timing, and in the TAS I was forcing a double jump with UDLRB right before landing to do the Air Walk. However, if you happen to find a platform above you at just the right height you can do an Air Walk with a controller.

1. Get below a platform. Use Jump Ninjitsu if necessary, although BaconOmelette in the below post mentions how he cannot get it working with Jump Ninjitsu and finds it easier with no Jump Ninjitsu. Which would ultimately be faster so that is good.
2. Hold Right and Jump such that the double jump height will be about the same height as the platform.
3. Jump to do the Air Walk.
4. For the OOB to work you have to then hold Down. 5)When near the ceiling release Down so the ninja will be in the ceiling.
5. Press jump. This will have you jump again since you are in the Air Walk state.
6. Keep holding right since the game will be pushing you left since you are in the ceiling. 8 ) If you released Down and got enough height you should be in the ceiling.

Video. No weird opposite directionals like in the TAS.

Further proof of it working on real hardware with retrospy input display.

That's an awesome discovery.

I recently spoke with Mike about the double inputs a controller can do, for example me being a PS4 player allows me to do the double input via D-Pad's R and Left-Analog's L.

I understand these things are practically impossible on original hardware, but I wonder if it constitutes a category of its own, it's interesting, especially when glitches like these are doable on practically all versions.

@VGCArchive Original hardware can do Left + Right inputs but it requires tampering with the controller and removing the "ball bearing" used for the D-Pad. It's generally a frowned upon practice to tamper with a controller to get a desired result (the Goldeneye Train mission went through this so I know) but I've stated before on discord that I would be okay with making a seperate category for it if there was enough interest to warrant its creation.

I wish I discovered and brought this all to light sooner, I feel that by the time I talked about it to Mike the audience for speedrunning this game has moved on, so on my part it was a discovery that was made perhaps too late? Who knows.