"Taxpayer received a letter from their employer stating they were in a combat zone and qualify for "combat pay" exclusion."

That "and" might be the problem. I think we are seeing a mix of terminology: combat zone vs combat pay; military members are the only ones eligible for that exclusion because of combat pay.

Contractors might qualify for a different exclusion. Having proof that they were in a combat zone is why they qualify:

https://expattaxprofessionals.com/blog/article/combat-zone-contract-workers-claim-foreign-exclusion