We actually don't use any information about your company page, or your individual CV, when deciding which jobs to show you. This will change in the future, though I don't have any estimates for you as to when.
There are a couple of things which influence the likelihood of seeing an ad for the company you work for, including how good of a fit we think you are for it, and how many job listings we have in your area (geography being the bigger factor). We only have 12 job listings within 20 miles of Auburn Hills, MI, so the chances of seeing that ad in that area is pretty high.
People may have mixed opinions about whether or not they want to see their own listings. For some, seeing their own listing is positive reinforcement - it shows that their listing is actually running, lets them see what other users see, and I think there are many devs who don't even realize their company is running ads on SO Careers, so when they see the ad pop up, they may have feedback to give their HR department (which we think is a good thing that should happen more often). Other people may react like you, essentially asking wtf? I'm not sure deciding on the correct behavior is as clear as you make it sound.
For what its worth, showing you an ad from your own company doesn't take away any impressions from your listing. We don't allocate a fixed number of impressions to job ads, and they're selected from a weighted random distribution, so the chances of other users seeing your ad aren't diminished by the fact that you are also seeing it.
I'm marking this as by-design for now since it's not even going to be possible in the near future. However, once we do start incorporating more data from Careers, we'll revisit this internally and we'll make a decision about what we think correct behavior should be at that time. I'm not promising we'll come to the conclusion you want though.