If the "10 false codes and the device is bricked" can be circumvented, there is a backdoor.
The 10 try deletion is a completely separate system from the encryption. If you stop it from deleting, the encryption is still intact. No one will be able stop this from happening short of Apple taking action or divine intervention, so there is no backdoor here.
What you seem to be pointing out is a philosophical point, about if in the future Apple designs software to backdoor your phone, then there is the potential for a backdoor right now, therefore, there is a backdoor right now. This is false. There is no backdoor. Apple, being god in this case, could make a backdoor. Apple, or god (which ever you prefer) didn't make a backdoor, so there is no backdoor.
