The idea of putting a time limit on what constitutes a grope is dumb to begin with. But, if somehow someone decided that was the right approach, 10s is absurdly long.
There are situations where there might be some disagreement over whether something is a grope vs. an accidental touch. Say squeezing past someone at a crowded bar, or on a bus/train at rush hour. But, that contact is on the order of 1s or less. If there were going to be a time limit for groping, a more reasonable idea might be that if it’s longer than 1 second, the chances of it being an accidental touch are much lower. If it’s under a second, then maybe the person being accused has grounds to say that it was just an accidental touch.