Account Sharing isn't merely the act of having someone else use your account.

It's the act of enabling someone to use your account in addition to yourself.

This also precludes things like an account held in someone elses name being used by a single person (Due to often a Parent/Guardian being named on the account because it's their credit card paying for it, while the child is the one that uses the account)

Thus, "Demonic Possession" would only count if you willingly gave the "Demon" your account information and so let them access your account.