He didn't knock it off he just made a redone version and he gave credit to the original creator!
Viewing post in Five Nights At Baldi's Redone comments
Yeah, that's right. I'm a big fan of the original Five Nights At Baldi's, and thought it was unfortunate that you can't really play it anymore due to Flash support ending (although as I've found, it is still possible), which is why I decided to make a redone version containing overhauls and improvements with my game development experience (while making sure to give proper credits as well). Which a lot of players seem to have enjoyed so far.