If the thief attempts to enter a new pin, it doesn't block them out. Technically, it is impossible for an installed app to prevent resetting the device, or creating a new PIN (unless it is a system app).
Regarding tracking with a new sim if connected to the Internet, that is only possible, if Avast Mobile Security is still installed on the device. Then it can keep sharing the location. However, if the new user removes it (device factory reset), it won't work.