NO. Walt would not have wanted this.
I have to disagree. What I think Walt would not have wanted was the current setup, where cheap, fake topiaries are wheeled into a rough shape of a path, Guests are directed into a 100% backstage area, where they pass by dumpsters that
reek of garbage, large delivery trucks rushing feet away with nothing but those fake plants between them and the Guests, the Cast Member smoking area and cafeteria, with full view of the Princess break room, as well as the pad Tinkerbell lands on. Then expect them to pop out on Main St./Tomorrowland and be immediately back in the "story" of the Magic Kingdom.
The bypass, unfortunately, NEEDS to be open on busier nights, because Main St crowding becomes a safety issue. So, if it
has to be done, what Walt would have wanted is for the area to be themed. (IMHO of course. No one can speak for what Walt truly wants except him)
Now, if it were up to
ME, I would make the policy to stop letting Guests into the park when it reaches the point that the backstage bypass would be needed, but that's not going to happen
So, this is the next best option, and much better than the current situation.