Why are comments disabled on YC-related submissions?

I saw a worrying pattern: hacker news seems to have "sponsored" submissions like http://news.ycombinator.com/item?id=2289425 where the comments are disabled and there is no chance to comment on the submission.

This worries me since it gives the impression that HN lost its impartiality - it is now offering the chance to a privileged group of people to by-pass the voting system and show to us content without giving us the system of checks and balances in posting and moderating follow-up comments that discuss the submission.

I really don't like it and I worry that something else might be compromised as well - where do you draw the line if you're willing to disable the comments for said submissions, maybe even give some artificial votes to the story... Does anyone else finds this worrying?