Has or Have?

Good Day,

I was wondering if anyone would be able to assist me with the following. I am trying to determine if the word "has" or "have" should be used. The structure is not that of a typical sentence as the information that appears prior to the em dash is the introduction for a few different paragraphs.

An employer commits an offence if they—

1) terminate a contract with a person because that person or any of his officers has disclosed a health and safety violation to the Department of Workplace Safety.

I was thinking that it should be "has" since it initially refers to the one person. But then I started to think that since it was either the person or any of his officers "have" would be more appropriate.

Many thanks for any assistance that can be provided.