I was having a nice introductory meeting with my local Toyota service manager (not the dealership I bought from...), and he very politely indicated that he would not turn it off due to safety issues, but he was willing to run it by the dealership's legal arm to see what they said.
Then, when one of his service techs got called into the office to get the info on the other items I wanted worked on, the topic was brought up again in passing and the the tech said that he was doing it all the time for Tundra owners, which effectively green-lighted the request and it was subsequently performed without issue.
I know others have indicated that sometimes it's who you talk to that matters - Just another story to verify this point.
For what it's worth, the flashing light stays on, just the chime goes away (at least for me), so there may be wiggle room with the safety aspect using this information.
DP