Is it OK to drive a LED matrix with constant current?
If you are driving the display full on and the Arduino freezes, you will almost certainly overstress the line which is currently being displayed. It may or may not produce permanent, obvious damage.

The article you linked suggests that a full-brightness screen will draw about 4 amps. Since this is a multiplexed display, with rows being selected, the average current for any row which is at full brightness will be 4/16, or about 0.25 amps.

Divide by 32 elements per row gives 7.8 mA, and dividing by 3 gives about 2.5 mA/color. If the address selection freezes, the full current (4 amps instead of .25 per row) will be applied, for about .125 A/LED. Depending on the LED rating, this will probably be somewhere in the range of 2 to 6 times the maximum rated current.