That's absolutely fine to do. Here's what's wrong with rants:
- They distract from the actual content of a post
- They offer a possibility for off-topic discussion and flamewars.
- They make you look unprofessional.
- In the long run, they make us – as a site – look unprofessional.
We don't want that. So, if you can, always remove rants. Be nice.
In this case, the original answer was a pretty severe example, and should have probably been deleted. Yes, I know it's a self-answer, but maybe the OP can phrase it a bit more elegantly.
Thanks for cleaning up the cruft. What you did was right, however, if it descends into a rollback/edit war, just flag them rather than engaging into a war.