Well I was watching gameplay of the Dominion gamemode on Exile, and I noticed at 5:28 in this video, the Blue Spartan begins the animation to assassinate the Red Spartan, but before he even gets to grab him fully, it just stops, and they both live.
I thought about it and maybe it is indeed a fix for the Assassination bug in Reach were if you body was going to merge into the geometry while doing an Assassination it would insta-kill the enemy you were assassinating, and the sound would play, but there was no animation.
However, someone I know suggested that for Assassinations, you have to hold the button down the whole way through for it to successfully kill them, possibly stopping the issue of people wanting to beat down and not assassinate.
I don’t know if it is either or simply just a new bug in the build, but the two suggestions above would both be brilliant.