You're right, lots of things could happen to neutron stars to make them slow or even stop with the right exchanges. The commonly understood model, though, was that these slow spinning objects would not be pulsars. The radio pulsar mechanism was thought to 'shut off' below certain rotational speeds
Was that based on theoretical or empirical analysis?
If empirical, is the data biased? The article mentioned ASKAP reads a lot of the sky at the time. If there are objects emitting every 15 hours, would that even be detected or just look like noise?
