Likewise, I have never in my life thought that this establishing shot was anything other than a regular Star Destroyer, and specifically, the one seen in the following shot, which is because this is how every film handles establishing shots. It is in fact, the very purpose of an establishing shot; it grounds us in the new scene, giving us an anchoring point from which to get our bearings and understand the material we're about to receive.
It would make no sense to show us an image with which we are intimately familiar with (the bridge of a standard Star Destroyer) yet intending it to be the bridge of an entirely different vesel, and then show us the vessel we expect it to be right afterwards, and only then, reveal the full ship. It makes no sense at all.
The only way that shot would be of the SSD's bridge is if the very next shot was... the SSD.