I figured it out, I basically concerted the ! to an ASCI code and it worked. Here is my syntax:
# ! Screening
arcpy.SelectLayerByAttribute_management(CISAddressSDEFL, "NEW_SELECTION", "NEIGHBOUR LIKE '%!%'")
explanationPointChar = chr(33)
arcpy.CalculateField_management(CISAddressSDEFL, "NEIGHBOUR", "!NEIGHBOUR!.replace(explanationPointChar, \"\")", "PYTHON", "")