I've never heard about it. What I have heard about those types of "treatments" are that its just a dealer cash grab. If the material on these seats need a treatment, Lexus would've done it.
I'd got a custom cut clear bra from the shop my dealer uses for 200 cheaper than what dealer wanted. Bumper, part hood, and mirrors. Already saved a rock chip on bumper. I think bras are worth it.
I wouldn't do it since I trust that Lexus is already taking care of you mostly. If I were to get some type of protective treatment, I would look after market because what the dealership is trying to get you to buy is simply an add-on to make them some more money in my opinion.