When Chuiee Thorpe arrived on Alderaan, he would’ve landed at an Imperial military base – symbol of the newfound “alliance” between the Empire and Alderaan, with the latter as a decidedly junior partner, or in fact a colony in all but name.
Thus Chuiee would’ve stolen an Imperial uniform for his disguise, rather than an Alderaanian one. This would have led to many Alderaanian officers giving him suspicious looks, seeing him as one of the hated Imperial soldiers to whom they were now expected to kowtow.
This resentment would be the underlying cause of the brawl in the Cantina, with the result that Chuiee (literally) disarms one officer and beheads another. However, as Imperial officers on Alderaan could be tried only in Imperial courts (like in 19th century imperialist colonies, or American troops in Vietnam), Thorpe would not be accountable for his actions in the bar fight… officially.
Later, though, when Chuiee was held captive in the dungeons of Alderaan, his Alderaanian guard would just see him as another typical Imperial soldier, hopped up on power and thinking he could do whatever he liked. As a result, when the surviving officer from the Cantina brawl came to visit Chuiee in prison – along with a couple of friends – all they would have to do is slip the guard some gold, and claim to be the prisoner’s “friends,” to get some extended time alone with Chuiee in his cell.
The net result would be that CJ Thorpe was held down and castrated (in the Chinese fashion, with everything removed). When Bail Antilles found Thorpe, he would be naked with blood-soaked bandages wrapped round his thighs. After Bail freed him, CJ would steal the uniform of his jailor; however, like Lawrence of Arabia in David Lean’s film, blood from his mutilation would seep through his uniform trousers.
By the ending of the film, Thorpe would have received new genitalia grown via Aquilae’s cloning program; however, as the Aquilaean cloners could not reproduce sperm, he would remain sterile.
Though this symbolism might seem crass, it’s in keeping with GL’s thinking at the time – being sterile would link CJ Thorpe thematically not only with Lucas himself, but also with George Washington (cf. the Emperor’s speeches in the 1974 rough draft quoting excerpts from the diary of John Adams). It also fits with the idea of the Empire in SW reflecting the sexless, emotionless dystopian society from THX 1138.