When you say professionals, in what specific capacity are they being recruited? Who is requiring them to sign an NDA? The Foundation? Their employers? I've worked with a number of Wikipedians in Residence and professionals at US cultural institutions, and I know some of them well enough to feel confident that I'd know of such a thing if they were forced to sign something like this. (Many people working with the private data of editors are required by the Foundation to sign a confidentiality agreement, but that agreement only extends to that data. I've signed it myself. I believe a copy of this agreement is publicly available somewhere. Meta?)
If this NDA requirement is true it deserves to be publicly exposed in the interests of transparency. If it's not true, it's a distraction from the real problems that exist in this community and enables those opposed to eliminating those problems to point to false claims in an attempt to dismiss attention towards those problems.
If anyone has one of these NDAs, please send it to me privately, anonymously if you wish, and I will take the appropriate steps to expose them.