No apologies needed for making a polite suggestion :)
That said, I don't think it's good advice, particularly not in our situation. Our kid will be lucky enough to have four loving grandparents, cutting them off from the great-grandparents wouldn't be a big loss.
More generally, I'm confident there is plenty of research showing that getting rid of toxic relationships - which this very much is for some - has a lot of value, and may outweigh potential benefits of grandparents.