Um, why would this plugin be relevant in the mu-plugins directory?
Seems it wouldn't be something that needs to be enabled for every single user all the time?
Also, a plugin in a subdir of mu-plugins won't work anyway. The main plugin file has to be located in mu-plugins or it won't be included.
The mu-plugins directory is really only for things that must be loaded for every pageview, on every account, regardless of what the user wants.
With a plugin of this nature, I don't see it as something the 99% of the people using it would want it run for every user. Better off to keep it in the plugins directory (which works as you would expect) for MU as well.
For the few folks that would want it in the mu-plugins directory, they most likely already would know to edit the file.