ToyotaCare should have covered diagnosing the rattle. When you look @ Lexus LX570 service records, they're full of "customer hears rattle" "radio not as loud as customer believes it should be" "FM reception not as good as customer's _________ (insert exotic brand here)".
IMHO, I would NOT go back to that dealership. The only thing I buy @ my local dealer is OEM small parts not easily available from ih8mud sources. A salesman called from a dealership where we'd looked into LCs, but purchased elsewhere. Upon hearing that, he said to call & he'd arrange any servicing we needed (1 hour distance).
I don't think I'd recommend that. That's similar to calling out a dirty dealer on Gunsmoke, nothing good is going to come out of it. You're never going back to that dealership, anyway. West Coast Expert? Why not admit your own service techs knows diddly about Land Cruisers? When my wife arrived here in 1992 with our 88 FJ62, she called to say there was an oil leak. She'd taken it to Toyota & the diagnosis was rear main seal. I called my local dealer's service dept. No way @ that mileage. Turned out to be the common oil pan gasket leak. When I went to the misdiagnosis dealer & inquired, the Service Mgr's response, well, the dealership has changed hands & the mechanics are upset with the new owners.
Likely answer to the rattle. We've never raised our headrests . . . 2019 LC . . . < 1K miles. No rattles. In all likelihood, I won't be taking our LC to the local dealership They'd shown no interest in ordering a new Blue Onyx Pearl LC for us. Why should they get reimbursed for our ToyotaCare maintenance?