This is JUST the sort of thing that would make Lexus' target demographic drive STRAIGHT back to the dealership and either yell at the service department to make the car STFU, or toss the keys back in the sales person's face. I know I would. If the dealer wouldn't take it back I'd then probably pull the fuse from the stereo or whatever gadget was giving me the ads (assuming it didn't disable the engine, which actually would further provoke me.)
Bottom line, unless the message is based upon a service interval and is EASILY disabled, nobody wants the vehicle they just paid 40k+ for giving them any sort of advertisements. Definitely suicide on Toyota's/Lexus' part.