It is at low frequencies.
"It can be seen that the loudspeaker becomes increasingly more directional above 1kHz in the frontal hemisphere as it transitions from omni-directional through cardoid to dipole radiation."
"Increasingly more directional" doesn't mean it is not directional bellow 1000Hz.
In that PDF there are front and rear measurements od LXmini from which you can see that it is omni up to about 200-300Hz. It gets cardioid pattern from 700Hz up to 1000Hz, and then gets dipole radiation pattern above 1200Hz.
Every loudspeaker is omnidirectional at low frequencies. This thread is not about those loudspeakers.