Simon, we have seen the damage and injury that can result from airsoft weapons when a "sober" person uses poor judgment. To imply that there is little to no additional risk from someone who is under the influence of substances which have been proven to impair said judgment is absurd.
What you or anyone else does with their free time is your own business. Alcohol, or other recreational drugs have absolutely no place during an airsoft game. If you want to light up after the game, with your guns safely stowed away in their cases, be my guest.