NTC Inrush current limiter datasheet
In a thermistor the resistance will change due to heat which is generated by the amount of current flowing through it. The resistance at 25 degrees C will be 10 ohm and then decrease as more current is flowing through it and it heats up. So the answer is no, it will not be unchanged up until 1.5A. It would be at a higher resistance if the line on the graph were to continue/ show more data. The data it shows the operating range once it's heated up.