Of course it was: there is nothing preventing a company from contacting the dev team and going "we've one quite a bit of work, are you interested in getting any of that upstreamed". Getting changes upstreamed is in no way the exclusive domain of fully open source projects, it just requires reaching out.
Just because there's a closed development model doesn't automatically imply the devs team lives and breathes "not-invented-here"-ism and are no interested in discussing improvements that make a difference to actual people using Lua in (extremely) large real world products.
Just because there's a closed development model doesn't automatically imply the devs team lives and breathes "not-invented-here"-ism and are no interested in discussing improvements that make a difference to actual people using Lua in (extremely) large real world products.