10 Huge Revelations From Star Trek: Khan

Captain Hikaru Sulu suffered at the hands of Khan Noonien Singh twice. From his point of view, Khan's death was no tragedy, nor had he any real interest in exploring what drove the man who tried to kill him. Sulu was the one tasked with shunting the Enterprise up to maximum speed after Spock's sacrifice and he was present at the funeral of that great man.

So, when Dr Lear petitions Starfleet to declassify Kirk's logs with the aim of proving the man guilty of condemning Khan, Sulu is incensed. The last thing that he has any interest in doing is vindicating the madman who killed so many of his colleagues. 

However.

While Sulu's anger is evident throughout his appearances in Star Trek: Khan, so to is his sense of duty and the difference between right and wrong. He may have agreed to take Lear to Ceti Alpha V to disprove her theory, but he does take her. He volunteers the Excelsior for the mission, even staying for longer than a ship might normally remain in orbit of a dead planet. 

He comes into mild conflict with Ensign Tuvok over Lear's investigation, ordering the young Vulcan to keep tabs on her. Clearly, he is not happy about any of this - but as shown, he allows Lear to complete her work, no matter the personal cost. He may be human but Hikaru Sulu remains a stalwart Starfleet officer.