that's because until the end of the book he didnt have said sword in question
im not too offended by logans actions anyway, every (playable) race except the sylvari are complete dicks to humans. the asura treat us as disposable idiots and thier ego makes them blind to how flawed they truely are. the charr have animosity against us for obvious reasons but 250 years of fighting plus the destruction of 2 human nations due to their actions is really going to make it difficult for me to like those fleabags. the norn still look down on us but at least of the races they are willing to give you a shot. its too bad they cant see past our small(er) stature until you beat them to within an inch of their life. so really i can see why he did what he did. even without her as a love interest Kryta is all the humans have left for all intents are purposes. so going to serve the queen is pretty much an act of self preservation for the species as a whole
EDIT: also to top it all off our gods have all but forsaken us so while most humans keep some sliver of hope in their hearts its really hard not to put the needs of your species above the needs of others when it really feels like the whole world is against you