G'day Ryan,
I think you'll find the particular quote you used,
(2) A person shall not, when acting as a member of the crew of any aircraft or being carried in any aircraft for the purpose of so acting, be under the influence of drink or a drug to such an extent as to impair his capacity so to act.
relates to crew members specifically.
I'm not sure whether the second part of the quote relates just to drugs or drugs and drink, it seems to imply that you can be a bit pissed/drugged but if you can act unimpaired it's OK which I find at odds with other parts of the regulations.
Regards,
BH.