Dunno it's just weird to say you're in the business of who you sell to instead of what you sell.

A caterer that only caters to oil camps isn't suddenly in the oil business, for example. To take an easier to understand example.

Or my brother in law runs a company that does CNC machining and sells to Airbus. He's not suddenly an aircraft manufacturer, even though his parts make it onto planes.

Shrugs. I have no issue with someone claiming that a company making drills used exclusively for oil drilling is in the 'oil business'. However, I would not call such a company an 'oil company', so I take your point...