Okay, I watched the set @
Gay Ginger
(great Zelda btw, you ruined that mac so hard lol)
If anything I'm more convinced it's a fine stage for Mac after seeing the transformations, but I feel like the Mac player wasn't playing as well (died to walkoff cheese early first stock [though he was playing poorly near the blast zone and deserved it], SD'd to a misinput second stock, the stage actually would've saved him third stock if he didn't panic upB into your fsmash) and very little of it was stage related. Though naturally Mac isn't going to do as well on any other stage as he does on FD.
Like, the only really bad transformations for him that popped up were at 6:58 (just camped it out) and 7:50 (the platform layout would've let you play really lame against him, though it didn't come up), and neither really had anything unfavorable happen for him, he just had to wait it out. The rest were all good to amazing layouts for him.