That is no proof against it though, considering they're only under the hole that he dug to get into the heart.Once again an invalid statement. The mobile has known things that the PC version does not have (like enemies, items and a boss), so that people from the PC version would have reported it is not a good argument.
In all seriousness none of your arguments were any direct proof against it. Not that I know of a heart structure being a real thing, but judging from the Mobile-unique things that I know of, they could very well have implemented a such a "heart biome".