The public benefit requirement under the Charities Act 2006 has been amended by the Charities Act 2011 and came into force in March 2012.
Though it covers same requirement ground your petition question is flawed.
Should this reach 100,000 signatures it would be thrown out in the first instance as the 2006 Act doesn't apply. Even though it would be clear a mistake has been made and the wrong legislation refered to in the petition question, Parliament like any other legislature processes on correct wording for questions like these and wouldn't make the necessary changes themselves to the wording of the petition question to take into account the mistake of wrong legislation being used.
Further, I would have thought an appeal to the Charities Commission under s46, Charities Act 2011 would be more applicable, as under s15(1) Parliament has given the Charity Comission the power to decide who qualifies under the 'public benefit' function. Therefore even a successful petition question using the correct Act of 2011 would mean that Parliament on debating the issue would delegate the repsonsibility to the Charities Commission as they already have done.
Just my two pennys worth.