Kibito totally could kill loads of people like that, though.
That wouldn't really be useful to him, since most of the villains can survive in space. He could use it if Vegeta ever got out of control, I guess. Or he could have used it against Dabra, but then again Kaioshin apparently could have rendered Dabra completely immobile, weak, and vulnerable at any time he wanted to just by waving his arm. So whatever.
Of course, the JSAT special and BoG seem to show Goku breaking this rule and teleporting around freely. We could hand wave this and say maybe he's improved his technique or is actually locking on to microscopic organisms or God knows what. But during the main series, Goku is consistently shown to be unable to teleport anywhere that doesn't have someone whose ki he can sense.
Or Kibitoshin just taught him the Kai Kai version. Logically, Mr. Buu should know that technique too. He saw it used a couple of times. Even if he just wasn't paying attention or something, it'd be trivial to teach it to him considering how fast he learns.
We know from Toriyama that Freeza isn't going to "merely" be revived, so while we obviously don't know the details yet, we can probably expect some sort of big power-up that will put Freeza somewhere in the vicinity of new-and-improved post-BoG Goku. Boo obviously wasn't able to do much against Beerus in BoG, so odds are he'd get similar results fighting Super-Duper Revived Freeza. Even if Freeza got turned into candy, we'd probably just end up with the World's Strongest-er Candy Ball.
Mr. Buu didn't even try to use his Candy Beam against Beerus in BOG, and Vegetto was only able to resist transmutation because he's Vegetto, not because of his actual power. I guess you could introduce a similar special resistance to Freeza- like, he's a god now so he can keep his power even after being turned into candy (but then why didn't Mr. Buu?)- but I think it's more likely that they're just going to forget Mr. Buu has that move again. Or, judging by the Goku-Gohan precedent, take it from Buu and give it to Goku.