A group of dancers hired to perform on stage at a conference is hardly an egregious example of exploitation, but what concerns me is phrases like 'I don't personally know...' and 'their best option'. The subtext being: 'this is something I wouldn't want to do, therefore nobody must want to do it, therefore anyone who does it must have been forced somehow'.
I don't personally know anyone who wants to be a sysadmin - after all it's a job that comes with high stress and very low social status - but I don't therefore assume that anyone who is has chosen it because it's their only choice.
If you are simply pointing out that a hardware or software conference is not the appropriate place for any display which sexualises women (or men for that matter) then we're in agreement, but it *appears* (and perhaps I'm misconstruing your position) that you believe a priori that no woman would ever want to be sexualised to any extent in a professional situation. A fairly short Google search can find any number of sex-positive feminists (and women who prefer not to describe themselves as feminist because they feel betrayed by feminism as a movement) who wouldn't agree and feel marginalised by that (common) viewpoint.