A Remux is when you mux raw m2ts files to mkv. This is a mux.

Muxing a BDMV into mkv format would be what most PTs would call a BDRemux. Technically we are taking an existing mux not muxing raw files of our own, hence "remux", so we consider the terminology correct. However you're free to disagree. Not like the anime community has ever agreed on much to begin with which is why there isn't any standards when it comes to tagging or naming. Anyhow, the description is copy & pasted on over a thousand torrents across a 6+ year timespan at this point. So we're unlikely to change or respond further to this topic.