I advise searching a couple forums to find him for permission first,if u cant then in the readme aknowledge him for his works and say you attempted to reach him but was not successfull. Just to avoid any drama NEVER just use someons sprites or coding and think its all fine and dandy cuz u said its theres in a readme. Ppl like ax or i who make it publically known that we allow our work as open source its cool to do that but when people spend a ton of time and effort doing everything from scratch will be lease likely to be like us. So just be respectful and attempt to ask first. This whole use anything of anybodys and say it after alls said and done rule DOES NOT EXIST! I like you flam and dont wanna see you pulled into drama for believing that shit. U can ask ark,hype,acey,topps,any multi character creator and theyll tell you the same thing: get permission first.
Hope this helps and enlightens the ignorance of the not asking dilemmas.