^
misa commited suicide aftere a year or so
There's no flaw
1. If he kills investigation team, he is definitely now Kira. A human. Not God. which contradicts with his beliefs.
2. If i had info same as near/mello my deduction would go along this line...
The reason Kira picked this time of year is probably because before Kira wasn't able to make a move due to his fear of L. Prior to L's death if kira was part of the investigation team, killing few members would be acceptable. Unless Kira was under suspicion Killing of "Kira-is-innocent investigation team members" would lead to Kira's disadvantage. Killing the people not supporting Kira only causes suspicion. But none of the investigation team died, meaning there's probably too little to kill multiple members of. And narrowing down the numbers does not help shake the suspicion away.
After L's death, killing them all related to kira incidents, especially japanese investigation team shows Kira is very confident. Therefore Kira is aware of L's death. Light surviving solely is obvious statement saying he is Kira, since Kira will not let a genius live. (since Light's name record/picture is everywhere, basically super intelligent son of chief of the investigation team, whom kira just had killed. The son hasn't been seen around lately. That leads to Light is probably a member of the investigation team. If Kira fails to see that and take chances with super intelligent son going around, it is suspicious)
If Kira wanted to kill he would have dealt it with heartattacks. But they "disapeared" which sounds like a cover up. Meaning that Kira is indeed part of the investigation team. Therefore he cannot just kill them all, but he has to make them disapear.
Sadly unlike geass deathnote can't give commands like "be loyal for me for the next 3 decades." doesn't work like that.
There is no gurantee Kira's bodyguard is not a spy. Code geass has too many plot holes compare to deathnote. Only thing similar about the two series is we have anti-heroes. The central ideas and theme involved in them are very different.