To be honest and fair with you, I'm really not sure what more Dreamwidth would have done about this, either, other than give you the same advice and sympathize.

If you don't want somebody contacting you, you do need to ban them. If they try contacting you through other accounts, that's a recipe for ban evasion, which is a suspendable offense.

And if you don't want somebody reading posts, they need to be locked. There really isn't any viable way to protect them otherwise.

It does suck, though.