crystal stability gone wild on higher speed microcontroller
The datasheet says the resistor may help with oscillator startup especially at higher frequencies. Therefore it should do no harm to enable it.

The crystal you are using is not too high for the chip, it supports up to 24 MHz. But to run at over 20 MHz, the supply voltage must be 4.5V or more. And the High Power oscillator mode must be selected for crystals over 12 MHz.

The crystal pins are very sensitive. Touching them with finger, especially the XTAL1 input pin 19, will disturb the oscillation and anything can happen - it is not normal use to touch them as they need to be very carefully isolated from disturbances. A finger to ground would short the input to ground at far below 1 Mohm resistance so it represents a significant shift in the oscillator DC bias and it will also add significant capacitive load in the range of tens of picofarads. The behaviour is different from another MCU, because they are built differently and have different internal oscillator circuitry.