(Libressl is developed by OpenBsd)
Once you write significant software, it's frequent that the NSA or police will offer you collaboration (eg. How CloudFlare started with Project Honeypot, or how Facebook got investment by the CIA, Crypto AG that got investment, etc).
The intelligence services don't have to coerce you through a gag order; they can just make a generous offer.
One of the LibreSSL author(s) maybe has financial problems. In this case, what is better for him ? Accept a juicy 5M USD consulting contract, be a nice boy, solve all the problems and beyond, or be the guy that will discover what it means to be sued to oblivion on frivolous charge (NSA will never charge you but they can share information).
If the US companies respect orders of the NSA, it's because they don't want to end up sacrified.
If the DoJ for example needs help from Facebook to capture documents from Airbus to give them to Boeing, you think Zuck will give away all his shares, stock, money, family, or just collaborate ?
The CEOs will fight the decision until they can (because of the PR risk), but at some point if the pressure is strong enough they won't be able to refuse (and I respect their choice to protect their families and by extension, protecting the families of their employees by protecting their job).
If someone knows your weaknesses he has unlimited power. It doesn't matter if it is a legal or illegal organization.
Yeah that's my first thought: why would they use gag order when they can just bribe someone? Doesn't even have to be $5MM; a few $100k here or there could change someone's life.
And then there are actual government contracts, e.g. how the US can dangle the GovCloud or other lucrative contracts over Facebook/Google/Red Hat/Microsoft/whoever, with some implied or explicitly demanded "add this to the stack..." requirements.