Players who played in very early access wrote that Astarion attacked if they refused to help him with a ritual. That the "path of the Spawn" was added later, due to the fact that these same teenagers wrote letters to Larian with snot and demanding to let them "fix" Astarion. Astarion began to be "softened" in order to make him "more palatable to the players". It's not him who needs it, but the audience of teenagers and bitchy female fans to suppress and "fix" him in the first place. And the aforementioned heterosexual men can let them do that, but the rest of us - be kind enough to romance those who resemble those very same heterosexual men's fantasies about themselves. Or - get punched in the face and know your place.
In Early Access, only Act 1 was available and there was no information suggesting that Astarion would attack the player during the ritual in datamined content. Additionally, it was obvious that there were possible "good" and "evil" endings for all characters, including Astarion.
