I must point out - objectively - that 'doing the right thing' in Yamatai is a somewhat skewed notion. Otherwise, there wouldn't be any United Outer Colonies.
The Yamatai Star Empire was described by a character called Mizuho as a nation bent on
jingoism. Wes and I don't exactly have the same values - so I don't expect him to agree with me - but I can relate with Mizuho there.
People in Yamatai do not believe they are 'bad people'. They consider themselves civilized, they consider they are an upstanding society, they largely consider that society an utopia and they - in general - are quite proud of being (or being in) a strong nation.
Yamatai, however, is an empire that assures it's prosperity through expansion and conquest. They extend their territory amongst the stars to earn themselves more resources. If they encounter another civilization in space, they will try to make them their friends... if that fails they have in the past disdained the choice of allowing neutrality in order to forcefully annex that other civilization... especially if that culture worked on values the Yamataian explorers found reprehensible.
Politically in the eye of interfaction dealings, Yamatai is very, very prone to gunboat diplomacy; they have a strong military, they know it, they are proud of it... and because they have a strong military they rarely see the need to compromise or play second fiddle to anyone else. This unfortunately paints the nation - to the surprise of some of its citizen when news gets back to them - into an interstellar bully run by tyrants. The latest ruler, Empress Himiko, has gone to lengths to try and repair the Yamataian nation's brimmed reputation.
Does that make Yamatai much different? Better? That's in the eye of the beholder, I guess. I've heard one person condemn Himiko for being too soft, another commenting on how Himiko's efforts aren't genuine so much as she agrees with how things were done previously and that she is a manipulator of popular opinion.
Regardless, Wes thinks the world of Yamatai and he's heavily invested in its ruling family and it's militant practices so I'm fairly certain reading up so far would have him frown and inwardly bristle. Sorry man, but this is my opinion. ^_^;
Now, as far as being a doctor in the Star Army goes, it's best to remember that you'll have a character in an institution that is willing to commit 'evil' in order to safeguard the empire (evil being relative to my perspective - sorry). If doing your duty means blowing up the face of an irritating diplomat that doesn't know his place, spacing a capture UOC soldier or bombing the surface of a recalcitrant planet that won't join your righteous nation (and thus is potentially an enemy) with deadly pathogens... so be it. It's all done so that your nation and those you care about remain prosperous and safe. What could be more honorable than fighting for family and kin?
And those others you help trample? Well, better them than your nation, right?
(I'm not being sarcastic. Just figurative.)
Your doctor will likely mesh best if he doesn't come to grip with his conscience on a Yamataian plotship. They just don't have quite the same values so it'd probably be best not to go in conflict there. What conflict I've seen, from other characters, usually didn't turn out well.