I flew from DUB to ADD via BRU recently. We were able to stay on the plane in BRU and await the boarding passengers. It was definitely more convenient than getting off, reclearing security, and boarding again, even more so if I'd had to board another plane (and therefore take the risk of a delayed connection etc). I don't know what the procedure is in the other direction, but I suspect that it might be the same, because Ethiopian in that case wasn't selling 5th-freedom tickets between BRU and DUB.
Now arguably a 2/week 1-stop service is not necessarily a big deal in terms of the overall connectivity that's on offer between DUB and PVG, but the fact that it was a Chinese airline is relevant because that's the way that a lot of Chinese inbound tourists to Ireland would choose to travel.