Vayikra Rabah 16:4: Hashem does not want Resha'im to tell His praise. Kli Yakar - it says (verse 5) "va'Yhi Hu Mesaper", and not v'Hu Mesaper, for just as Gechazi was about to begin, she came, and told the king (verse 6).

Kli Yakar citing Mahari, Malbim (4-5): Elisha's merit helped that she came at this time, and Gechazi affirmed her words.

Ha'Mikra veha'Mesorah p.80: Above (4:13), Elisha asked her if she needs him to speak to the king for her. The Navi's words are not Batel (like Ramban Bereishis 48:15 says about Yakov's words about future sons that will be born to Yosef)! Here, [discussion of] Elisha helped her when she needed to speak to the king. Refer to 8:6:3:1.