I understand we all have the right to an opinion -- but we all have the right to an opinion.
Being white doesn't make mine more valuable than somebody who is black.
Being a man doesn't make mine more valuable than somebody who is a woman.
Having a home doesn't make mine more valuable than somebody who is homeless.
A good idea is a good idea regardless of who came up with it. We can't make progress by devaluing some to build up others.
There are laws against hate crimes and general discrimination. So if somebody posts a petition which is clearly racist, sexist, antidisestablishmentarian or discriminatory against things like sexual orientation or age; be good moderators; take it down.
Most don't want the government patrolling the internet, but their own website is an exception.