The method setFreezeTicks is arbitrarily limited to getMaxFreezeTicks (The value of which is the point where the entity starts taking freeze damage) despite vanilla allowing much higher values.

This can be seen by spawning a chicken and running:

/data merge entity @e[type=minecraft:chicken,sort=nearest,limit=1] {TicksFrozen:30000} 

Which will successfully set the entity's freeze ticks to 30000, causing them to soon freeze to death.