I'm late to this discussion and it's probly all been said but no I don't think a petition would or could have any impact on lawmakers. It would be impossible to enforce non-shunning and it's unrealistic to expect lawmakers to make people do something they should be deciding for themselves regardless of the rules of the dubclub.
At the end of the day it's the responsiblity of every individual JW to stand up to WT and say no to shunning.