Note that the comment was if the interviewed developer asked if the company used any Arduino - not the reverse.

But I can't see any problem with the question anyway. Arduino is a platform well suited to one-off test equipment. It is obviously not a tool for 100 or 1000 or 1k volumes of a product, but that is irrelevant. When you have a one-off problem, it's nice to be able to pick up some existing LEGO pieces and quickly solve that problem.

Many companies do not have own products that can be tweaked/abused into solving small one-off problems. And with the availability of the Arduino, many have the ability to pick up the hardware even from a local store specializing in hobby and technical devices.

Another thing is that a lot of test equipment is created by students who come to different companies to do some final projects before they graduate. Then it can be quite good to give them some Arduino hardware and tell them to google a bit before starting with the project. With the Arduino hardware, they can ask most questions on the net, instead of bothering some inhouse resources.