NDA are used so the people who "work" for BTCS keep quite.
Because they are a public company stock ticker " BTCS "
I am sure all the people who work at BTCS " transaction verification services" had to sign in blood.
But hell what do I know. Right padrino
Just caught this post, maybe not blood but something real close

I have a whole stack of NDAs, each and every one on the front page of hardware now that I think about it... When negotiating prices, lead-time (which feeds speculation on supply chain, yield challenges, etc.), for larger customers no company is interested in having those details spread around given it's competition sensitive...