I have two main issues with this suggestion.
Issue one:
21st's currently has two sub-units that have models and jobs, Keller's Unit & Special Operations. This is the same amount other battalions have and have been allowed since the beginning of the server.
The issue arises where you wish to take a sub-unit that has no model difference or job difference & replace it with a whole new set of models and jobs. This will put 21st at a point where they have 21st/GM | Special Operations | Keller's Unit | Jet's Unit, all separated out in different jobs.
Keep in mind, 212th attempted to have Ghost Company added in and everyone also shit on that idea too.
Issue two:
Currently the biggest issue within 21st, as per discussion with High Command, including Marshal Commander @NobleHeoruwulf, Specialized Regimental Command (and Ex-21st Commander) @Gadget & even the new BCMD @Oxen, is that there is no unity within the battalion and the sub-units are very divided.
By adding in another unit, we are pushing the unity of 21st and the cohesiveness of a battalion that is meant to be working together as one unit, further and further away to grow into a bigger issue for someone else to fix down the line.
I personally cannot support this suggestion due to these reasons. -1.