The whole alcohol debate grinds my gears, if in moderation, Yes, of course, it actually loosens people up and can make them have more fun, this is a proven fact, so, guests can have a lot more fun in your park if you serve alcohol, I'm not saying that they won't if you don't etc. But, they should have got to a point in serving that man alcohol where they realise that he's reached his limit, you have to blame the people serving it for that.
It's the same in the bar I work (I've worked there for 3 years), if you can see someone is becoming drunk rapidly, you put a "DNS" (Do Not Serve) on them, so nobody will serve them any alcoholic beverage until they've clearly sobered/gone away. This is a universal trick, the park have obviously not put this into fruition.