> At what point does 'accepting' an alternative set of morals become 'condoning' them?
As far as I can tell, those words mean practically the same thing. "Condone" is modernly generally only used in the negative sense, and thus people may be confused into thinking it means something akin to "endorse" or "support". In actuality it means something much more akin to "tolerate".
"pluralism" and "relativism" are harder words to nail down. One way might be to say the relativism says that all moral systems are equally valid while pluralism says that there are more than one valid moral system.
Here, I think "pluralism" is being presented as its own moral virtue (rather than as a philosophical stance): tolerance of other moral systems and beliefs is good.
> pluralism in general tries to leave people alone to pursue their own ends as long as they’re willing to play nice with others. Part of playing nice with others for pluralism is not trying to coerce others into adopting your truths, values, and ethics, even if you think you’re right and the other party is wrong. That live and let live attitude may be the same practical result as relativism, but it is reached by starting at a different philosophical standpoint.
http://blogs.bu.edu/dscott/2011/06/24/pluralism-vs-relativis...
So I guess the point being made is that while a lot of sexism is bad, especially where it is imposed unwillingly, there there may be acceptable sexist moral systems that limit that sexism to voluntary participants of that moral system.
However, the choice of voluntary participation in the moral system is usually suppressed in sexist moral systems which makes them unacceptable from a pluralist stance.