The lack of weapons is not an homage to the brady compaign, it's a realistic restriction of an experiment. It is much easier for the medical staff assisting the colonists & actors to react to blunt truma injuries, cuts, scraps etc than it would be for them to deal with an arrow or gunshot wound. The later could easily be deadly before the medical staff could react to treat the injured.
While I agree the colonists put security too low on their priorities, you can't make it to the exclusion of the others. The the heat of the region they're in during the summer, they need to secure at least some drinking water very quickly and food can't wait very long either. Yes, they should have done a lot more than they did early on, but ignoring the need for food, water and supplies to focus solely on security would have been a mistake too.
Some physical security and basic weapons would have helped immensely, but most people in the US don't think like that because they're comfortably unaware of how dangerous desperate people can be.
As for a maurading group only being after medical supplies, that is more realistic than is sounds. There are 3 basic types of mauraders in deperate times: 1) Justifiers 2) Looters and 3) True Marauders
The first group are generally good people driven to raiding / marauding because they feel their survival depends on it. This people will justify their actions as acceptable because they "only take what they need to survive" These are the kinds of people that steal a loaf of bread to feed their kids, steal medicine because they can't afford to buy it, etc. They don't "want" to steal, it's "wrong" in their minds, but they can justify it to themselves. When pushed, most people will fall into this catagory.
The second group are oppertunistic. They take things because it's available and the social penalties for taking it are lifted. Looters will typically take what's available rather than what they need, but are rarely determined enough to fight heavily for things until they feel they need them. This is where most "Mobs" fall.
The last group are the most dangerous. True Marauders look at strength and force as a method for aquiring wealth (it's a job). True Marauders will take anything of sufficient value regarding the amount of effort required and may use excessive force to intimidate as a way of reducing the amount of effort required in the future. While this type of group is often in the minority, they often rise to power after the collapse of authority because they have the strength to enforce their will on others and they can provide needed supplies and protection to others.
The group portrayed in the first episode of The Colony was obviously ment to be the first, driven to raiding by a persieved need for medical supplies. They didn't take anything else because they didn't justify to themselves their need to do so.