I think “a mamin” made an excellent point.
A poster further back said “as long as its only women, who cares what they do”? There is a clear lack of thought that went into that statement? What if they had pole-dancing classes, women only? Is that okay, too? Obviously not.
To be blunt, dancing like a zona is 1000% assur even if nobody is watching. It’s even worse if others, particularly men, are watching. But it’s still 1000% wrong even in total privacy.
But as someone else wrote, anyone (regardless of gender) who condones this terrible lack of tznius is clearly lacking in sensitivity to what it is to be tzanua.
To spell it out further, if you participate in immoral dances “with women only”, you’re guaranteed to be overall changed by this and, therefore, in front of men, too, you will also (to some extent) FOR SURE, dress/behave/act inappropriately (to some extent).
As to the ridiculous comment about tennis and house-cleaning, tennis is not intended to highlight the body and is not inherently non-tznius even if *might not* be advisable to play in front of men. On the other hand, Zumba and Latin American body dancing are clearly intended to highlight the body, which is completely antithetical to tznius.