| The point is, man(1) has to find the underlying file.
You want to think of this from the encoding point of view, rather than
decoding. There should be a canonical encoding, for any given name,
which is what man(1) would be looking for. Any files that happen to
exist which would decode to the same thing, but aren't canonically encoded
would simply not be found. As long as you apply the same canonical encoding
routine all the time (when creating files, and when looking for one) there
is no issue at all. If someone decides to ignore that and create other
files, they still can, they just don't work properly. Tough.
The canonical encoding form can be whatever floats your boat, but I'd
suggest most chars represent themselves, except when that doesn't work,
and in that case we encode that char .. and of course, as in my mistaken
interpretation of your question, always encode the magic char).