The 2 spam replies aren’t being done by bots; they were made by actual people. A bot wouldn’t have left a referring URL, especially not one that makes its tactics obvious. So this “spam” was actually created by a real person who took the time to read your page and post a relevant comment. I don’t see the problem here. So what if they link to their own site? Thats the whole point of letting people put in a URL. I don’t see why you would allow personal sites to leave a URL, but not commercial sites. And how would you draw the line? A lot of personal blogs are supported by ad revenue. And so what if he doesn’t put in his real name, but instead uses a name related to his buisness? I frequently post anonymously (like now), use a pseudonym, or the name of my blog. The internet doesn’t require that you always use your real name.
Obviously all blogs have their own policies for determining what is acceptable and what isn’t, but I think you are shutting out a lot of people who are making a contribution to your site.