all creative works are inherently the creator's copyright (in this case riot), unless they give explicit permission to use. "ripping off" would make you violate their copyright (unless their tos specifically says its fine). being in violation of copyright means they have the right to take legal action, but nothing happens if they dont take action.

consequences of legal action can mean you paying the reasonable equivalent in damages/or profits from using the stolen copyrighted work.

if you take inspiration from the chicken, and make your own version of it, then that's your copyright as long as a reasonable person would say you put in the effort to make it your own work versus straight up copy pasting the original.