Why does it say "Al la'Melachim l'Mo'el"?
Rashi: L'Mo'el is like la'Kel, like "l'Mo Fi" (Iyov 40:4. It is as if it says l'Fi; the Men and Vov are extra - Ibn Ezra there).
Malbim: Due to your deeds, you are no longer considered among kings, for kings do not drink wine.
Why does it say "Al la'Melachim Sheso Yayin"?
Sanhedrin 70b: Bas Sheva rebuked Shlomo why should you be with kings who drink, get drunk and renounce Hashem?!
Rashi: It is not nice for kings to get drunk.
Refer to 31:4:1:2.
What do we learn from "ul'Rozenim Ei Shechar"?
Sanhedrin 70b #1: Bas Sheva chastised Shlomo 'you know all the secrets of the world. Will you drink and get drunk?!'
Sanhedrin 70b #2: Bas Sheva chastised Shlomo 'those (the Sanhedrin) who engage in the secrets of the world, seek your counsel every day. Will you drink and get drunk?!'
Rashi: "Ei Shechar" is like Ein Shechar (they should not drink).
Malbim: Also Rozenim (officers who counsel kings) should not drink Shechar. They may drink wine 1 , but they should not drink Shechar, which intoxicates.
Perhaps this refers to Yayin mi'Gito (grape juice). (PF)