Eagle Arms did not "start the AR-15".
Eagle Arms, one of many, many, manufacturers of AR-15 rifles, simply bought the rights to the name Armalite.
All the Armalite rifles, tooling, blueprints, etc. had been sold to Colt's (about thirty years prior).
Eagle Arms (now aka Armalite) then started manufacture of complete rifles under the name Armalite. (Their stripped receivers, AFAIK, are still marked Eagle Arms.)
They (meaning Eagle Arms, by whatever corporate name Eagle Arms chooses to call itself) did not , in any way, shape, or form, "start the AR-15".
They did re-establish the name Armalite.