I was told that quite recently, a year or two ago, an Ops Wing on a FJ base was referring to the resident FJ Sqns as its "customers".
Seems a pretty reasonable approach to take. The resident Sqns require certain services and functions for them to do what it is they do. The station provides those services and functions - ATC, Admin, MT etc etc. The rotary world understands providing a service to it's customers (mostly the Army) and the word has been used in service provision lingo for many years now.
If I provide services, why shouldn't I see those I provide to as my customers and seek to keep my customers happy?