"To work for XX" could mean "to be an employee of XX" or "to work on behalf of XX." When XX refers to a
company (
公司), more likely than not it means "to be an employee of XX" (In contrast, the Chinese phrase 為XX公司工作 is normally interpreted as "to work on behalf of XX公司"). However, when XX refers to a
person (
人), it can go either way, depending on the context (e.g., "Nobody wants to work for Trump." vs. "I work for God.").
"运营商" (or 營運商 in my dialect)
is grammatically a "人" (e.g., "公司法人", "企業法人", "財團法人" 的 "人"; cf. "台商", "奸商", "官商勾結" 的 "商"). We may say "在XX公司工作

", but NOT "在XX營運商工作

" because 營運商 is a "人", which calls for "在XX營運商那裡工作", "在XX營運商旗下工作", or ambiguously "為XX營運商工作".
最近,一位同事通过为纽约世贸中心一号观景台运营商工作的熟人的邀请,约好带我们一起去参观一下世贸一号观景台。"
最近,一位同事跟我們約好一起參觀紐約世貿一號觀景台。他有熟人為該處的營運商工作,故有此機會, 能攜伴免費入場。
營運: 經營, 營業運作 (譬如, 掌管收售門票).