I find myself wondering whether a stronger emotional punch wouldn't have been if our villain of the hour had been an old war comrade of Sinclair's OR Ivanova's, with his willingness to go after aliens directly tied to his experience in a genocidal war.

Oh, that would have been wonderful! I was thinking something similar during Sinclair's bit about how "We had a saying; the only good alien is a dead one" - compare it with his line next episode about how after the Battle of the Line, for years afterward he had to fight the urge to strangle every Minbari he saw, and you kind of wonder how much Sinclair was just saying what he thought Home Guard wanted to hear, and how much of it was real feelings he used to have...