The following is my personal beliefs and do not speak for the unit or command staff.
A lot of people under estimate the logistical aspect to running a unit, especially one similar to the scale that this is already at. First and foremost is money. The obvious respond to this would be "more people = more donations". While that is technically true. You would be surprised to see with the amount of donations that come in, how hard it is still to pay servers, the website, TeamSpeak, and other things that go along with it. Donors and stuff that needs to be payed don't scale similarly. The price of things vs the amount of people that those support is not proportional.
For example, if it costs a unit of 100 people, $100.
It does not cost a unit of 200 people, $200.
Granted this is just a made up example, it would probably cost closer to $350 for 200 people.
Another thing that people don't realize is the additional just sheer man power that goes behind it. People don't do this as their jobs. Because we don't only simulate military customs in game, but out of game, there is a large amount of "clerical" work that goes with it. I know me personally, just helping out, I have put about 120-140 hours into working on things, and I can't imagine what all the behind the scenes things command staff has done that members don't see. There is no reason to outgrow something based on interested, especially when people can easily come and go. There are still much infrastructure that is yet to be built. And the unit shouldn't be running before its at the track meet.
Lastly is the idea that we shouldn't limit our player based. I personally disagree with that. The matter of the fact, is that the unit being more "exclusive" will do two things. It will allow the people who want to be here, be here. Those people will work to get here. And secondly, it will increase retention. Over time, the player base that is here, are the ones who are truly dedicated to the way we play, and what we do. This will cause less disciplinary issues, higher attendance, more people who will likely volunteer their time, etc.
Personally, the last thing I would want to see is the unit growing based on interest. I'd rather see the unit grow based on leadership and other aspects like "hey, we got the logistical power, the monetary power, the interest, and I think SGT Victory would make a good leader" rather than "well damn, there are a lot of people who want to join, we gotta open another platoon".
Does any of these mean the unit can't grow past that? No, if there are the means, it can be done. But from 1SG Shepard's post, it doesn't sound like it, and has been debated for some time.
Again, these are just my personal opinions on the size of the unit and recruitment.