This is based on the implied consent doctrine. By being US citizens and obtaining US passport (property of Federal Government), you consent to obey laws and such.
Regarding to application of state laws, it depends. Some states/municipals do have extraterritorial jurisdiction authority. Generally, courts have ruled that your permanent residence is the determining factor when it comes to general jurisdiction. Anyway, Congress also does have extraterritorial jurisdiction authority hence the list of laws per the link you provided. Those were passed to clarify or strengthen existing laws. Our federal legal system is pretty much a reactive one…it usually passed after a loophole was exploited or such.
Controlled Substances Act prohibits marijuana and it doesnt explicitly state that it is only applicable within the borders. This law was applied routinely for drug-related offenses happening outside of the US and folks were convicted. However, a few years ago, a court of appeals – I think 4th circuit-- overturned a conviction … saying that CSA does not apply over sea. As result, the House passed another Act to clarify/strengthen the intent of CSA, but it did not become law yet.
Back to original post… as federal employees and contractors, implied consent applies. You are expected to respect and obey federal laws regardless… this is something we agree on, I hope.