defectors, detractors. It was Azerbaijani Airlines, headed to Grozny, so maybe a passenger from either of those regions? Azerbaijan is in intense conflict with Armenia and highly dependent on Russian support. The region is deep in conflict, and strongly authoritarian. Plenty of people people who would need a strong message to understand that they're not as independent as they might think.

Of course you have to evaluate the facts yourself, but it's healthy to have some critical perspective.

Why would russia shoot down a plane if it was someone defecting TO russia?

"In politics, a defector is a person who gives up allegiance to one state in exchange for allegiance to another, changing sides in a way which is considered illegitimate by the first state." - Wikipedia

You can have defectors internally in the country. In Russia, defectors have a tendency to fall out of a window, regardless of who might be walking on the street (collateral damage).

Nonsense. You would catch the person after landing instead of downing an entire plane.