How did Facebook feel about you publishing the algorithm publicly? Specifically the Sharp+ version, as it seems that some part of that originally derived from existing Instagram code. (if I understood it correctly - or was it just an additional sharpening matrix? regardless, it sounds like something they might have wanted to keep proprietary)
I put the Magic Kernel into the public domain in 2011, long before starting at Facebook. Yes, the Sharp step is nothing more than a three-tap sharpening filter, not at all remarkable in itself, and yes the "+" is just extra sharpening with the same filter to match existing properties; it was convenient in practical terms in that it did not require extra processing, but is not special in itself.
