I have been pondering this issue, because it really bugs me - no, it worries me. A *lot*.
The only really functional difference between a manual chair and a powered chair is... the power. It seems like that shouldn't really matter, but stick with me for a minute.
A couple of years ago, we noticed that suddenly, bus drivers were always standing up on the step whenever an
ECV or power chair was loaded. Since I'm curious, I asked a bus driver one night why all the drivers were hopping up on the steps now whenever anyone drove a personal mobility device up the ramp, and on to the bus. His answer? They were being trained that way now. Too many drivers had been run over by folks who were unable to control the throttle coming up the ramp. Ironically enough, on our last few trips, I noticed that some of the drivers now actually walk backwards towards the front of the bus as they try to "guide" you into your parking spot, so clearly the steps aren't the only "safe" place for them, but - and here's where it all ties together...
...What if this is a response to a situation where people have (inadvertently) knocked the throttle of a powered device during transfer to the ride vehicle, leading to a dangerous situation with a potentially out of control device? (And yes, I understand that it would only be "out of control" for a moment, but if it "bucked" and hit another Guest or CM, a heavy power chair could do real injury)
It's the only thing that makes any sense to me. Otherwise it just seems like Disney has decided that everyone who shows up in a motorized personal mobility device *can* transfer until proven otherwise, and we know that isn't the case.
Here, in this space, we (corporately, as a group) recommend that folks *not* rent a powered chair for WDW unless they use one in their daily life at home. WDW is not the place to learn how to drive a powered chair, and not only are
ECV rentals less expensive overall, but the ECV in general has a much shorter learning curve, and most of them are equipped with a throttle that will stop further powered motion if you take your hand(s) off the throttle. Newer models are quite comfortable as well. Additionally, historically Orlando supply houses wouldn't typically rent a powered chair to someone who didn't have one at home. If you tried to lie, and say you had one, the first question they would ask is "What model is it?" so that they rented you the most similar type of chair.
Sadly, there are still folks who will rent a powered chair, when what they should be using is an ECV. Although I don't know for sure, I have always presumed that those people either believe that the powered chair will be more comfortable - or it will result in some sort of preferential treatment (that no longer exists with the
DAS system). And a certain percentage of those folks are downright dangerous, because they think a power chair works just like an ECV does. And it doesn't.
There are very few other reasons I can think of that would invoke the "safety" word, other than someone blazed through WDW in a rental power chair, and left a trail of destruction and injured CMs and/or Guests in their wake. I could certainly see WDW making some changes after a scenario like that, but I feel like that would have been discussed around here by now!
A Guest who insisted that their device stay with them in the ride room - but maybe the brakes didn't hold? That would also be a safety issue, and a big rolling one at that! But forcing every device into manual mode doesn't line up with that theory.
A Guest who couldn't make the transfer to their place between 2 of the "Banshees"? That might be/have been a problem, but that is resolved by asking the Guest to wait for an end spot on the next ride so they can pull up next to the Banshee. It shouldn't require manual mode.
The only other thing that seems even remotely possible is... is it possible that some of the cheap knock-off powered chairs (that have flooded
Amazon in the last couple of years) maybe emit some kind of electrical interference due to unshielded electronics? I don't know enough about how that ride operates to know if that kind of interference would cause an issue for that type of ride and its controls. Or, maybe it isn't the controls, but the video system - the actual flight video - that it interferes with?
It's all speculation
Were I in your shoes, I would *call* Disability Services at WDW, and just indicate that you are following up because you haven't gotten a response yet. I understand why you reached out to DVC, but I really do think that any "policy" related answer will most likely, ultimately, come out of Disability Services.
I hope you get a real answer. And for all of us, I hope it makes sense!