Restrictive clauses are not set off by commas, and yet we often see commas deployed this way, even in the work of mainstream journalists.
This is the lead paragraph in a piece by Ronda Kaysen in today's NY Times:
"In the suburbs, homeowners take their lawns seriously. A neighbor, who maintains an impeccable bed of grass in his backyard, once spent a full hour explaining to me how he’d had a sample of his soil analyzed to help him attain optimal growing conditions. He glanced at my backyard and suggested I do the same."
To me, the sense of the construction suggests that it is indeed restrictive, because the pertinent (or restrictive) trait of the neighbor, which merits his mention, is that he maintains an impeccable lawn. The commas are included in error. Am I right?