Mute City does have cars for you to wander around on at ground level, so it's not like there's a complete gap in the middle. Lots of airspace though, but I think even Little Mac could survive this stage. He'd have to wait around to Rising Uppercut from the cars to the upper platforms if someone is on that platform, though, so he definitely wouldn't enjoy it. Also I discovered, interestingly enough, that this stage can have gaps in the damaging floor depending on where it is on the track. How did I find out about this? Because a CPU player epic failed their recovery and fell right through the aforementioned gap to their death. I was entirely expecting them to bounce off the damaging floor and return to the stage, but instead they fell past the edge of the road and died.
As for someone complaining that Ganondorf has trouble on Tomodachi Life: What are you talking about? From what I've seen, Ganondorf absolutely loves this stage! The outer blast lines are super close so he gets KOs very easily (like you die at 75% if he gets a Smash Attack, FAir, or BAir on you), and the square-shaped "everything is a drop-through floor" layout makes Ganondorf's low mobility a lot less of an issue, and gives him very easy ways to get past projectile spam that normally shuts him down almost completely.
People seem to think that circle-camping (or to be more accurate, circle-stalling) on Tomodachi Life will be a problem, but personally I've found the opposite: the stage very much discourages camping by making it much easier for prospective campers to be approached from any and all sides. Also, as I mentioned above, characters like Ganondorf have a lot less issue coming up from below or dropping down from above than they do covering ground horizontally, giving them a way to more reliably approach faster characters, and since they have a reliable landing space to work with regardless of where they go they don't have to worry about potentially having slightly sub-par aerial neutral game. For Ganondorf in particular, he can corner relatively fast characters by approaching them diagonally from the centre, allowing him to threaten every "escape" route with his surprisingly fast and long-reach attacks.