Should Political Polling be Banned?

I would not ban polling but I would certainly ban announcement of the results of presidential elections until the last polls (in Alaska/Hawaii, I assume) have closed. Let people finish voting before you start telling them who’s already won.

Since when are polls legally binding?

I don’t see a reason for banning political polls here. The poll results affected the election results. So what? One of the attributes of a free society is that people can say and do things that changes what other people do. That’s a feature, not a bug.