Are you saying Jay Miner created Genlock or just that it was forward thinking to include on the Amiga?

I'm not sure I'd agree with either, as I don't recall the Amiga having Genlock abilities at all. Only 3rd party expansion cards gave the Amiga the ability to Genlock to external video sources so that it was in sync with the rest of the house. For proper Genlock, you have to have some sort of input (typically a black video signal) to use as a sync source, and I just don't recall an Amiga natively having any kind on input like that.