What the hell ... -_-
1) Iruka would never even dream of being a Jinchuuriki - his parents were killed by the demon, why on earth would he want that in his body then?
2) He wouldn't have been able to handle Kyuubi inside of him, even if he got just a bit. That foreign chakra probably would have killed him because his body can't take that. Naruto was perfect as host for the Kyuubi because he has the large chakra reserve from the Uzumakis, and their bodies can handle the large, foreign chakra of the demon
3) No, Iruka wouldn't have been called a Jinchuuriki then - you're only a Jinchuuriki when you have the whole demon sealed inside of you, not just a tiny part
4) If he killed Naruto, Kyuubi would have died too - and later would roam free over the world, which is what the shinobi nations try to avoid. Plus do you really think Kyuubi would just sit there and watch idly how someone tried to kill Naruto? Even when he didn't want anything to do with Naruto in the beginning, if someone tried to kill him, he would have reacted and attacked right back because it is in his interest that Naruto keeps on living. If Naruto dies, he dies. It's that simple.
Plus I really doubt Iruka knows how to unseal a demon.
And then I haven't even talked about how big out of character that whole thing is.
So no, he would never do that.