Huh? Chris is telling the truth, as someone who does 3d work as a job..
Once you have an asset, like say a Gorrella, or any ship on trek.. All it takes is someone to animate it.. Granted, it takes time and money still put it on screen, but lets take a look at shows like The Flash, or even better, Stargate Atlantis..
The flash doesn't run around a "Real" city.. when he's running, its ALL CGI.. except when there doing a face or body shot.. so somewhere in whichever Cgi company.. they have Star city assets, and all the other assets the've already made..
Think of it as the old "Bottle Show" where you use sets that are already created to save costs on that episode..
And I pointed out Atlantis becasue the main place, atlantis is All cgi, and through out the 5 year run, they kept on adding more assets to there library to where they can do flybys in jumpers all through the city, or shots from one place to another..
For a Green Lantern series, it could work, but maybe at first make it a 13 episode season, and have as many practicle effects as possible, including people in makeup for aliens.. but over time, you build up your asset base, and dont have the expense of "Creating" new assets as often in the folowing seasons, so you just have to pay for render time and people animating things instead of people who build things... and it is as simple as Chris said, just retexure a made model ( realativly easy) to make it a glowing green.. Also, the constructs Don't have to be "Perfect" constructs, you can have basic stuff like a cartoony proportioned elephant, or a simplified cannon.. especially if they have a green glow to them.. so that saves on your cgi budget.. becuase the more complicated the model.. the more time it takes to render a shot..
So, in my opinion, yes.. they could do a decent Green Lantern Live action on a tv budget.. will it look corny at times? Yep.. would you have to make compromises.. Yep.. alot of an episode be dialog.. Yep.. but also Yep.. it could work nicely!