I think the current vote is building toward something good here. That said, some thoughts...
Assuming we're letting her leave if she wants to leave, the question becomes "what news is she carrying back to Nerima, and will that news result in something that we want"?
Overall, I don't think we actually want Chizuka's group to join us. Chizuka herself we might want (in spite of the fact that she appears to be willing to kill civilians as a side effect of using powers that give her slightly more tactical advantage), but based on currently available information her teammates aren't worthy of the loyalty she's giving them and the fact that she is loyal means that she won't join up without them. If we invite a group of girls who are explicitly untrustworthy to become our subordinates we start risking issues like "they are murdering people and not telling us", "they're passing information they have as members of the city to hostiles outside it", and "they'll turn on us in battle when they get a better offer". Those aren't things that we want to deal with.
At the same time, it's important to give a coherent party line because she's going to pass on whatever we say to others, and they might pass that on to others. Thus, the basic "you can work for me if you're not awful" message must remain intact even if we suspect that the specific people receiving it are, in fact, awful. If there are not-awful magical girls in Tokyo who hear rumors of us and what we're up to, we want them to know that they're welcome.
But Chizuka said "we need this territory", which means basically "I will be back again with reinforcements if you don't demonstrate to me why that's a worse idea to attack you than someone else before I leave". As a Tokyo magical girl it's likely that she will interpret our refusal to inflict significant injury as inability to do so, meaning that in spite of the fact that she lost this one she'll still have Nagamioka marked out as a relatively soft target- if she can just get enough support with her to take out this one troublesome girl. I don't know that we can afford to have her sharing both the messages "she said we can come live there if we follow her rules" and "she was better than me, but not way better and I was outnumbered", because that leads to the logical conclusion of "we'll tell her that we'll follow her rules, move in, and kill her if and when she causes trouble" for someone who is all of desperate, ruthless, and untrustworthy, which Chizuka's teammates apparently are.
To me, that means that the "pace her and give our standard set of immigration laws" vote is good, but it needs to be accompanied by a directive to give a show of power of some kind such that the message brought back to Tokyo is that we didn't kill her because we didn't want to rather than because we couldn't. How, exactly, we should accomplish that I'm not sure, but I do think that it's very necessary if we're not interested in needing to muster up a posse to throw back a full-blown invasion in this area within the next couple days.
The vote could also use minor refinements like "keep with her up until the Tokyo/Nagamioka border, but don't cross it" and "have Minami track her movements in Tokyo until she meets up with more girls, then see if she can pass descriptions/imagery of them to Maiko", as well as a set of general directions for the likely case that Chizuka just keeps moving and we're left wondering what to do after we hit the border (go back and talk to our native new contractee, probably).
] "Hey come back! If I wanted you dead, I would've killed you!"
