Genuine pearl grips were seldom, if ever backed with another material. Jay Scott FAKE pearl grips were laminated over a more resilient plastic to keep them from cracking. Perhaps this is where the "backing" info came from.
MOP is brittle, but fairly strong. The "note" on the link above simply absolves the seller of replacement liability. MOP is one of the most beautiful natural handle materials, Patton notwithstanding.
Many older Colts and S&Ws (and lesser brands) were offered with deluxe pearl grips-none backed. The reason MOP is not seen as often is that shells large enough for grips are much more difficult to obtain today.
Again, Los- I post from genuine experience, not reading on the Internet.