Suppose a security screener was staggering around reeking of alcohol. Should a pilot report him/her if he/she notices?
Much though I respect pilots, some of you come across as slightly precious sometimes. I voted that pilots should not be automatically breath tested - that would be overkill. But as an ordinary member of the public, if I had a reasonable suspicion that someone planned to fly an aeroplane while drunk I would tell the police. Why should a security screener be different? It's just one link in the chain that keeps us safe.
Do I think a pilot would decide to fly a plane while drunk, or that his/her colleagues would allow it to happen? Of course not. But I'm not going to rule it out at the 10 million to 1 level, which is the level current passenger flight safety is maintained at by constant attention to detail, multiple checks and redundancy in systems.