Why not just leave the double-quoting requirements intact. An unquoted <any> or <sameuser> (etc) would represent the special keyword while the quoted version would mean that the name is used literally.
For users that would be worse than not quoting. Then if they look up users they can't say WHERE username =ANY (users). They would have to do sumersaults like CASE WHEN username = 'all' then '"all"' =ANY (users) else username =ALL (users).
The whole point of having a view should be that you don't need to know the syntax rules for pg_hba.conf to interpret the data. If you do then you might as well just write a parser and read the file.
