Check out what Achernar said in the bug discussion thread(that I quoted some pages ago) to see why your logic is wrong.
When you enter the ethereal plane, you avoid damaging the swashbuckler and you only care for your char's safety. According to him(and on his theory Dulrik, but in reality not so much 

) your char should have no will to cast such a spell or activate such a device. That's the idea of taunt. That's why you can't quaff a WoR potion(unlike when hit by BoG's nimbus for example).
And mechanics wise speaking, the swashbuckler can't harm you really when you turn ethereal unless he has access to the scripted items that can make him ethereal too. I've explained earlier tactics that will either break taunt or make you leave the place faster than a swashie linking taunt attempts on you(because spam taunt lags him, unlike spam quaff word or spamming a direction).