The execution of Shimei ben Gera marks the closing of a historical circle, where a past curse is inverted to bring blessing and stability to the royal house. Solomon's elevated status is recognized by both heaven and the people. The primary approach among commentators is that the nation praises his wisdom and absolute justice. He showed no favoritism to Shimei, despite their close relationship as teacher and friend, punishing him severely for violating an oath to God [מצודת דוד, חומת אנך, אברבנאל]. Conversely, others explain this blessing as proof of Solomon's innocence. He is free from sin and not guilty of intentionally trapping Shimei. Instead, Shimei's downfall was orchestrated by God as a divine punishment for his past wrongdoings and his disrespect toward David [מלבי״ם].
Consequently, David's throne is made strong, repaired, and enduring [מצודת ציון, ביאור שטיינזלץ]. This newfound stability stems from two key factors. First, God actively avenged David's honor [מלבי״ם]. Second, and most importantly, the royal throne remains morally spotless. David's original oath not to kill Shimei for his earlier curses was never broken. Shimei was executed solely because he defied Solomon's direct order and violated his own sworn word [מצודת דוד, אברבנאל].
Typically, executing senior figures at the start of a new reign can shake a kingdom's foundation. In Solomon's case, however, the exact opposite occurred. The public fully recognized the justice of the verdict. They understood that Shimei acted foolishly and brought his fate upon himself. As a result, the kingdom only grew stronger and more secure [אברבנאל]. Ultimately, the fierce curse Shimei once uttered returned to his own head, making way for an eternal blessing and a throne that stands firmly before God forever [ביאור שטיינזלץ].