Expendable

• According to Merriam-Webster, expendable can mean "normally used up or consumed in service" or "more easily or economically replaced than rescued, salvaged, or protected." So, something that's expendable is considered unimportant, whether because it can be easily replaced or because it isn't intended to be durable or permanent in the first place.
  
  

Scruples

• Merriam-Webster defines a scruple as "an ethical consideration or principle that inhibits action." In other words, scruples are moral or ethical beliefs that prevent the people who hold them from committing unethical acts.
  
  

Meaning

• With the definitions of these two words taken together, the meaning of "expendable scruples" becomes clear. The phrase refers to moral principles that are easily done away with or ignored.
  
  

Applications

• People who have expendable scruples are not simply without ethical standards -- they claim to hold scruples but will ignore or forget them in certain situations for their own convenience. Some people earnestly believe in their scruples, but find when it becomes difficult to act within those moral guidelines that their belief simply isn't that strong. Others pretend to have scruples in order to look good, then dispense with the act when it no longer serves their needs.