The guy in question is not flying planes. That comparision is absurd.
And I gave an example that proved that you are wrong that has been in place for decades.
As an employer I have the right to hire or fire who I choose for whatever reason I choose. I don't want employees working for me who do drugs. I don't care if they do them at home or at work. Someone who is addicted to drugs is not trustworthy and has a proven weakness and deficit of character that I choose not to associate with and certainly will not employ such a person.
I also have no interest in hiring anyone with tattoos for similar reasons.
Lets face is millions of people are out of work and looking for a job, and I can afford to be picky.