I'd love to see all the paperwork and planning that preceded the work :).
This is specifically proton irradiation as opposed to neutron.
It doesn't appear to come for free.
Makes sense, the basic mechanism seems to be mediated by increased interstitial diffusion. Shouldn’t really matter if it’s protons or neutrons that are generating those interstitials
Edit: on re-reading, it doesn’t seem that they’ve actually performed any neutron irradiation experiments
The safety and sustainability that enticed e.g. Andrew Yang to like thorium are actually coming from low-pressure coolant and the concept of breeding, both of which are possible with thorium or uranium fuel cycles. The thorium itself has nearly nothing to do with either benefit. It's basically a rebranding of non-light water reactor nuclear.
Thorium has one major primary physical differentiator, which is that it alone allows breeding with slow neutrons. Uranium needs fast neutrons to breed. Both options have pros and cons that basically wash out.
What makes the LWR non-viable since 1980 or so is not the uranium or even the LWR, but the steam turbine it is attached to. The power density of a steam turbine is at least an order magnitude less than that of the gas turbines that are used to generate electricity today. To a first approximation, the cost of something is proportional to it's volume or mass.
As it turns out, even if the heat was free the steam turbine alone attached to an LWR would make the cost of electricity uncompetitive. In fact, this is what mostly killed coal.
If nuclear power is going to have any economic impact we have to ditch the steam turbine for a closed-cycle gas turbine and ditch the LWR for something that operates at higher temperature. Unfortunately the last time people were writing about the topic seriously (1970s) people thought the motivation to go to another reactor type was that we'd run out of U235, not that gas turbine generators would come online and wreck steam turbine economics.