Shakespeare was very careful in his plays not to utilize suicide in contexts where suicide would be considered an unnoble way to die. In his Ancient Roman plays, he uses suicide as a manner of noble death. In Julius Caesar, Brutus, Cassius, and Titinius kill themselves as noble gestures: they know that there can be no nobility in continuing on the course they have set themselves to, and therefore they determine that suicide is the most noble way to rectify the situation into which they have walled themselves.
Arguably, we can contrast the nobility of Brutus's death to the death of Caesar, which is not chosen by Caesar himself and does not reflect upon him in any particular way, as he has no agency in it. Indeed, he cries, "Et tu, Brute?" as he dies, knowing that he has been killed by his own "angel," which does not reflect well upon Caesar's judgement in life. By contrast, Brutus, in dying, says he "shall have glory by this losing day" in making the correct judgement. He prevails upon Stratus to kill him, saying that he will do so if "thy life had some smatch of honor in it." In being complicit in Brutus's suicide, then, Stratus is committing an honorable act.