Frankly, those kinds of restrictions are not uncommon ("heirs and assigns"... but unlikely enforceable in many contracts or settlements).
When drilling company Range Resources offered the Hallowich family a $750,000 settlement to relocate from their fracking-polluted home in Washington County, Pennsylvania, it came with a common restriction. Chris and Stephanie Hallowich would be forbidden from ever speaking about fracking or the Marcellus Shale. But one element of the gag order was all new. The Hallowichs’ two young children, ages 7 and 10, would be subject to the same restrictions, banned from speaking about their family’s experience for the rest of their lives.
I'd like to see Range Resources try to enforce a restrictive covenant on speech for the two when they are in their twenties.
But then again, with all the fracking who says they are able to live that long?
It also allows these company's to buy off people and say there are no "documented" complaints about how awful fracking is.
People love their water-taps to burst into flames.