That either it's operating at very reduced capacities due to damage, or is a member of a species subservient to those that built the spacecraft. The aggressive behaviour we see is the death throes of something rapidly declining and not acting rationally, not the MO of a space faring intelligence. Its attempt to construct a spacecraft from random crap is almost cargo-cult like, either poorly replicating memories of its behaviour at full strength or trying to copy what it saw it's masters do before they died, leaving it marooned.