The advantage of making the statements on-list are the knock-on benefits. Others who are offended benefit from the visible debate and visible show of support. I would suggest it is advisable to make the decision about private vs on-list resolution of issues on a case by case basis.
I would heartily suggest that gay people have had to put up with enough crap that goes well beyond the ordinary. I think it's perfectly fine to call people out on using terminology like poofs. It's not a matter of never saying anything offensive ever, it's a matter of respecting individuals and being basically respectful.
We all share the same space here, so we need to find a way to get along.
Free speech, well-used, is about being able to discuss issues freely and put forth bold ideas. I don't really think that casual slurs against minorities is what anyone had in mind as the central use case...