Willi - It may not be an option at your dojo, it is in fact an option at some. Hence the search.
I suspect some dojo's would be willing to consider a no breakfall policy for a person based on their physical limitations.
All I am saying is that it is not possible to replace every breakfall with a roll. This is simply a technical statement, not a question about dojo policy.
Of course he can chose to sit out techniques that require a breakfall, nothing wrong with that. Actually, many of the older guys here do that.