Is Duke consistent?
Will they do a check on the political opinions of all members of the board and all execs of all their suppliers? Are they going to send out forms to all suppliers to check on their politics or just pick on one? I get a form to sign, as a supplier to universities, where I have to state that I am not involved in modern slavery. I'm sure that is tremendously effective in ending modern slavery, although I am often tempted to write 'Friday is very happy with his duties' and see if anyone notices.
Blacklisting a company because they don't like the politics of the CEO, is damaging to all the employees of his company and their families. So they are targeting lots of little guys who probably dislike their boss (most people do), for a bit of virtue signalling.
And what about the users of the library? Are Duke happy about letting people in to do research on political issues that may lead them to write unpleasant things on their blogs. Surely that would make Duke an enabler of online hate and harms, in a nation where online posts may be regarded as dangerous, but guns are easy to buy. Will they be analysing what use students make of their time at Duke? Will they be only letting library users in if their politics match those of Duke's board?
Operating a business I don't give a toss about the diverse politics of my suppliers or of my customers, because I believe they have a right to hold and voice opinions I dislike if they wish. I don't have a veto over other people's thoughts and speech and expect them not to have a veto over mine. Because that is what free speech is all about. And nobody should value free speech more than a university, where academic freedom is fundamental to everything they do. The moment you add caveats to that, you are no longer upholding free speech, and have begun the slide down to state censorship, book burners and fascists. Like encryption, free speech requires absolute adherence. Take a bit of it away, and you have taken all of it away.
So, I buy from and sell to all sorts. Lib-Dems, Labour, Tories, LGBT, Neo-Nazis and Brexit supporters. Even Man City fans. Because I respect their right to be the people they are. That's how we all get on with each other. The alternatives usually lead to conflict. If I want to disagree with them, I will write a response to their blog post. Because that is the civilised thing to do.