Now that there was a lot of fiery discussion, I would like to sum up and answer my own question (since I don't think it has been tackled properly yet).
Can I dispute a decision to remove a comment?
There does not appear to be functionality in SE sites for disputing deleted comments in particular. One way to ask for other mods to double-check is to create a meta post such as this one.
It would be more convenient if there was some functionality to see what's happening with your comment. E.g.:
- See comment's state in your activity feed: flagged, deleted etc.
- See how mods are discussing its fate (even read-only would be ok for a start).
- A single chance to ask for extra moderation.
Now, from what I saw, the comment was just gone, even from my activity history.
Can something be done about biased and unfair moderators?
The question is not "should something be done", it is "can something be done" and the answer is Yes. There was a similar question asked about this in another meta post (community wiki).
The accepted answer there suggested that if there was no way to resolve the issue using site functionality (e.g. no way of asking for extra moderation), one could use the contact us form to contact SE directly.
Other ideas
Maybe SE is doing that internally somewhere in their databases, but if not, it could be useful to track complaints about mods and reevaluate them by SE employees once in a while.
In general I think mods in SE sites are doing a great job and having them is a great idea. The question is about the rare cases when they don't (and from other people's support, and other posts on meta sites I see it's not the first, nor the last case). Please don't take things personally.