Disclaimer: I'm not a Datalog expert. I do work for a company that makes a relational graph knowledge management system (RelationalAI), that has some Datalog-type aspects, but I only dabble at the front-end/query-language end of that; I work on the storage layer. I've also never used Datomic or its offshoots.
Yes from what I understand, Datomic works only with binary relations. Classic Datalog can work with full n-ary relations. (However any n-ary relation can be thought of, or logically recomposed, as a series of binary relations anyways, and vice-versa)
Syntax also clearly is not the Prolog-ish syntax of Datalog "proper."
But my point above is, Datomic is but one product and implementation of these concepts. It's a wrong take to make a statement like "The problem with Datalog, and Clojure in general are the licenses"; there is a field of many products, all with multiple licenses, and also weird to make this "Clojure" swipe, when there's only tangential connection between "Datalog" and "Clojure" based on one product (and its offshoots).
Syntax also clearly is not the Prolog-ish syntax of Datalog "proper."
But my point above is, Datomic is but one product and implementation of these concepts. It's a wrong take to make a statement like "The problem with Datalog, and Clojure in general are the licenses"; there is a field of many products, all with multiple licenses, and also weird to make this "Clojure" swipe, when there's only tangential connection between "Datalog" and "Clojure" based on one product (and its offshoots).