"If time travel is possibile, where are the tourists?"

Stephen Hawking asked that question and even organised a reception for future time travellers, but in our continuity, no one showed up. In many time-travel sci-fi, where actions have lingering consequences, visiting Professor Hawking in that reception would be forbidden. And I'm pretty sure it is now with the ART.

But before they knew it was a problem? I'm pretty sure someone visited Professor Hawking and even snatched him from the timeline at that exact reception. Can we be told that story in some future book, please?

What other scientists and luminaries should be at the top of the list to never make available the knowledge of time travel now? I'd say Hawking and Einstein are at the top of that list, but who else? Maybe Dyson, Dirac, Everett (of the Many Worlds interpretation), Penrose, Schrödinger, or, to name a more contemporary one, Sean Carroll. Any other suggestions?

PS: in her latest Chronos book, Rysa Walker had a character reveal time travel to Einstein. I'm not sure she herself understand the magnitude of that, but I really hope she follows up on it.