Can you define a split policy or split rule on a field without a domain? When a domain is involved, you can set the default value of the field and chose a rule for when a feature is split or merged.
The setSplitRule exists, but the only two options are 'None' or 'Ratio'. 'None' sets the attributes to the copy of the original value. http://resources.arcgis.com/en/help/main/10.2/index.html#//018z0000004v000000
I am looking to set a field to the Default Value (null) instead of copying the value from the original feature.