and accusing them of being executed by their own government like a 9/11 Truther?

Because Putin has a track record of getting the FSB to do exactly this. It's how Putin started the 2nd Chechnyan war after the 1999 Moscow apartment bombings.

It also fits pretty flawlessly into the FSB direct action playbook, and convenient avoided anything governmental.

why are you making jokes about a fictional video game (clear evidence the propaganda works)

Because OP started it, but mostly because that reference was a lot shorter than typing out the whole thing. Unfortunately, I realize most people aren't quite as up to date about the excuses for Russian wars or conquest other than the current one.

Innocent people have died

And that sucks, but I can't help but compare this to what Russia does to other innocent people. This seems kinds tiny compared to, say, dropping a scud missile on a grozny market, killing 200 women and children. There are mostly Muslims in Chechnya, so I guess they started their war a long time ago?

Primarily though, ISIS hadn't claimed responsibility yet. And even if they have now, that doesn't preclude FSB involvement.