By the "law" they are released once their season ends. So if they did not qualify at Sectionals they were released. By what their school coaches (or in a few rare cases the schools) request they may not be "released" unless they are not coming back to cheer school again. They may schedule camps, fundraisers, clinics, etc to keep them going until the tryouts for school in May/June.
There is still a protect my turf mentality between school coaches and All Star coaches just like in other states. Perhaps more so here because it is considered a sport and it is very competitive. Some schools will work with the All Star gyms, some wont for fear they will lose kids to the gym. And the reverse is true with All Star gyms fearing they will lose kids to school cheer. There are just as many recruiting issues between school cheer and All Stars as there is between All Star gyms. Typically the gyms and schools that make peace and find a way to work together and set acceptable boundaries end up being the stronger school programs.