Most people older than twenty two usually have more than one moral system. How same person behaves in different situations and medidates in different contexts may easily display the variance of general principles behind one's thoughts and actions. It can be difference between idealism and pragmatism: "in the ideal world all weapons must be abolished; in the real world I keep a small arsenal at home, just in case."
It can be difference between "us" and "them": "they must go to fight for the glory of our motherland, but me myself I'd better stay home."
It can be difference between public and private lives: "when I'm asked to preach about firm moral principles, I advocate celibacy and abstinence and I condemn those sinners; otherwise I love a good steak and a good fuck and I don't give a shit about those puritans."
It can also be difference between calling this trait "flexibility" and "adaptability" when related to those one likes and calling it "hypocrisy" and "double standards" when related to those one hates. After all, people with double standards is a good subject to have double standards about; and being flexible about people who are flexible themselves is nice as well.
Corollary #1: when making implications about person's moral rules, it's better to be extremely cautious, just because you never know how many of those one has.
Corollary #2: when person speaks about "firm moral foundations", the safest option is to ignore that altogether, just because it can really mean virtually anything.