Forst about the kill credit...I have had occasions where I dont get the message, but I notice that it showed up on stats pages. (IE, the guy in the Ki61 did it, and I know for certain that my Ki61 kill total went up even though I never got the message). Maybe thats what happened to you?
Second....well, technically its not cheating, because the game rules allow it to happen. True cheating requires breaking rules, like hacking into the flight code. (Bad idea to try, BTW)
It isgaming the system" in an unfair way, like killing a squaddy when youre chasing rank. You cant do anything about it except get mad, so for me I've decided to just let it go. They're the ones missing out on improving, after all. And sometimes when I've thought it was "death avoidance" I've later realised that they didnt even know I was there, and they were dtching to get a goon or something.
If done deliberately, it is definitely unfair and wothy of 10 minutes scorn.
BTW, I consider some "gaming" to be legitimate...almost like a clever exploit of a game feature. For example, having a parachuted pilot hide in the maproom, or having him camp on the aircraft spawn point to get collision kills (HT closed that loophole, btw), or using the shore battery to hit GVs on the beach below.