Is working for a company under contract to the US military “official government business” under section 20?
No. You work for that company. What they choose to have you do or work with doesn’t matter.
It’s a case by case basis. Many government contractors deploy people to non disclosed locations on official US government business. If you can tell your mom where you are traveling to…you should probably disclose it on your SF.
Foreign Travel for contractors can be tricky. The key is traveling on US Government travel orders.
Don’t know how many rounds this topic has been up and down the chain over the years.