Ah, it looks like we have a small misunderstanding. I thought you were talking about uncompressed video, which is enormous. This is only used in HDMI cables for example. A 1080p60 uncompressed video is 2.98Gbit/s, or about 1.22 terabytes per hour.
A remux is “uncompressed” in the sense that it isn’t recompressed, or in this case transcoded. A remux is still compressed, just to a lesser degree than a transcode. This means the files are indeed larger, but the quality is also better than transcodes.
To clarify the article’s confusing statement: they claim that remuxes can reduce size by throwing away some audio streams, while keeping the original video. This is true, but the video itself hasn’t gotten any smaller: you are simply throwing away other information.