All I'm saying is the poll was probably open, ie. responders don't pick from a predefined list, and Tunisian comes to mind before Arab. If you do restrict it to a list with only Arab and Amazigh as relevant options, Arab would be picked by basically everyone. I'm not saying Tunisian is an ethnicity. Like everyone else, we're a mix of a lot of different flavors. Simply that Tunisians would say that first.
But something needs to be said, in the real world, Tunisians do absolutely consider themselves Arab, and there really isn't this identity crisis people on the internet constantly speak of. It's one of the most homogeneous countries in the world. No region or sizable community in Tunisia has a special language or religion or religious subgroub.