I don't think it would be a bad law to introduce, to be honest. But before being enforced, it really should be, well, introduced, shouldn't it?
I think Granit's biggest mistake was to not even pretend to be trying to get the ball. Had he dived in, he'd probably have got away with a yellow, whereas the sheer, naked cynicism of just ankle-tapping him clearly offended the ref's spirit of fairplay.