Are you missing the other arm of the 'or'? Try the following, which assumes 'except' returns null if the second parameter equals the first.
(or someone
(except 'Apple some-company))
As a general style, although somewhat inverted, I prefer 'tailing syntax': (or
(except someone 'pg 'rtm '_sh)
(except some-company 'Apple 'Weyland-Yutani))
Sorry... I couldn't help it :)