I think the ads were fine.

I think the reason he did not include comments is the lack of a way of contacting people on HN. Very few people include an email address in their profile.

HN could help him a lot by adding a "email me" link on the profile page - not an email address, but a forwarder, HN will send the email.

I don't think spam would be much of a problem since you would need to be a registered user to send an email, and you could require 3 karma or something.