I cannot see the flaw in the logic I am afraid. The Home Office didn't either when they wrote the purple guide, and the BSI commitee didn't when BS 5839-1 was written, but it could be we are all wrong. The more time you buy for a disabled person to escape, or be assisted with escape, the more you move them towards equivalence with able bodied people. All disabled fire safety boils down to creating equivalence for disabled people, which is a worthy objective. The extent of the benefit may be in question, but the fact that it is a benefit is somewhat indisputable. Other than wave a magic wand to give them back their mobility, I cannot see what else, in terms of timelines, we can do, and to perform such a miracle would take a Principal Officer, and they are all too busy doing other miracles.