Only? 
In contrast to the physical Zettelkasten, the “Zettelkasten” in Luhman’s head was a biological neural network. Connections between information arise “by themselves”. Like all exceptional talents, Luhman simply thought … all the time. The “cross-references” (or whatever you want to call them) of a Zettelkasten are not the starting point of your own thoughts. It’s rather the other way around. Information can be archived, genius cannot.
I don’t know much about such things. But I know how it works for me. I think about something over and over again. I look at pictures, read texts. Then I take a break. Then I read the same text again. Start thinking again … and sometimes … sometimes a new thought suddenly arises 
What science are you talking about? There is rarely (never?) just one concept and one context from which you can draw exactly one conclusion.