TBH, I really like that Astarion draws a line there, where most characters won't. It's good for him to set boundaries, and I don't like when the game bends itself to cave to the player so they can get away with whatever they want rather than setting limitations- and there's also a dialogue that's now triggerable where, when confronted again about being with an illithid, he says "Even I have my limits, darling"
