"whether the exclusion they stated is tied to form 2555, I dont know.  They referenced nothing in that letter other than they were employed in a combat zone."

Yes, and that was a fairly recent provision related to the presence test:

https://www.irs.gov/newsroom/new-law-makes-clear-combat-zone-contract-workers-qualify-for-foreign-ea...

They are noting something important, but they don't know if it applies to the taxpayer.

https://www.taxesforexpats.com/we-help/army.html

This went nowhere:

https://www.everycrsreport.com/reports/RL33230.html

And don't forget: "Taxpayers choosing the foreign earned income exclusion cannot take advantage of any other exclusion, deduction or credit related to the excluded income. This includes any expenses, losses or other items that would have been deductible had the exclusion not been claimed."