What do you mean can he only do this to you?…

You have HIS ID on ignore, so he won’t be bothering you with any messages.

And you have to set your messenger on “ignoring all ID that are not on your list”, so you don’t get the hundreeds of ghost IM pop-ups.

Of course, in this case, you ignore people that want to talk to you in good intend, but don’t think to also send a add to list request. That’s, I’m sorry to say, collateral damage. (So In case you exchange IDs with someone in real life, be sure to tell them to first send a friends request.)