Larian could add 5 types of Lord Astarion's strikes if they so wanted to show that he could scare the player with something.
This could perfectly be done if the player broke up with Astarion, before the battle, to show his behavioral, attitude. The player doesn't want to - Astarion does.
There are so many possibilities. Kissing is not one of those possibilities.
When the player wants to, the player doesn't hit Astarion, and kisses him, no fear, kisses him.