Since you're not using Auctiva checkout, I believe this to be an eBay issue. However, I've forwarded your case to our engineering department for their comments. I'll reply to your case when I hear back from them.
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .