I don't know about prostitutes, but one of my good friends works at an upscale strip club here and her clientele does primarily consist of tech workers, especially whenever a conference rolls around.

I wonder where did that claim originate. Maybe there's some grain of truth behind it? Or maybe it's just people remembering news like this http://www.mercurynews.com/ci_23753946/12-child-prostitutes-...

The protesters are professional activists, the progressive's progressive. They're not impugning the morals of tech workers. They probably called their colleague in activism at the sex worker's support organisation and asked if they wanted to come to the protest.