Diane I think Mike describes the situation well there.
Losing the ability to walk alone does not mean bedridden as pwc can allow so much ability to stay mobile.
But when the torso, neck and arms are not working, the means to drive the pwc become useless (my PALS was using a chin control pwc towards the end, but it was so exhausting as his neck was so weak, and hitting any bump caused him to swerve).
Even though there are head supports for the pwc and they have tilt in space, it can become too difficult to support their torso and neck well enough without causing breathing and swallow problems to escalate.
Chris spent so much time in his raiser recliner, but in the last 2 weeks he found that he couldn't recline it back much at all or it interrupted his breathing, but sitting up in it he couldn't hold his head up well enough. I used so many pillows to recline the chair and yet prop him forward so that the foot rest would be up enough to get him almost comfortable.
He knew, that had his breathing not been so debilitated he was nearly at the point of being bedridden, because even though we could get him in and out with the hoist, we couldn't keep him positioned well for long once out.