It's true that no large scale Thorium reactor has been built yet. It's also true that its mathematically, chemically, and physically impossible for Thorium to pose the same radiation threat that Uranium poses under load.
Now, can Thorium reactors be good, or great? Sure thing, but for the time being all their purported advantages are on paper only, while the PWR reactors are in wide use.
MSRE specifically refers to the Molten Salt Reactor Experiment [1], which was a reactor that burned only Uranium, never Thorium.
By the way, the Department of Energy is collaborating with the private industry on a number of advanced reactor designs [2]. There is only one molten salt reactor and that one uses Uranium or Plutonium, not Thorium (see [3], slide 3).
[1] https://en.wikipedia.org/wiki/Molten-Salt_Reactor_Experiment
[2] https://www.energy.gov/ne/articles/infographic-advanced-reac...
[3] https://www.nationalacademies.org/documents/embed/link/LF225...
The current environment of Nuclear Plant technology does not negate the benefits of MSR Thorium reactors