Correct.
Knowledge consists of, roughly speaking, thoughts.
(a "justified true belief" - per https://plato.stanford.edu/entries/knowledge-analysis/ - is a kind of thought)
The "thinking" part of a "thinking being" - that also consists of thoughts.
If your knowledges are someone's property, you are someone's property.
A society where all knowledge is proprietary, is a society of ubiquitous slavery.
Maybe multi-layered, maybe fractional, maybe with a smiley-face drawn on top.
Doesn't matter.