They are up against big fossil fuel tycoons like the Kochs. If we are strictly talking corporate propaganda, the fossil fuel industry has plenty of that.
The most obnoxious thing about the energy literature is that it frequently reads like a stopped clock. People still compare the cost of nuclear energy to the cost of coal, but it's no accident that the US stopped building coal plants at the same time it stopped building nuclear plants because it stopped both for the same reason... The capital cost of a gas turbine generator (even in a hybrid cycle including a steam turbine) is dramatically smaller than the steam turbines used in coal and nuclear plants.
Since molten salt reactors run a lot hotter than LWRs they could drive
https://en.wikipedia.org/wiki/Closed-cycle_gas_turbine
but it's a technology that is not very well developed. If nuclear energy is going to compete with natural gas, however, they need to ditch the steam turbine.
Is the closed cycle gas turbine also using a superior cycle like the Brayton? Oh it's in the third sentence, CTRL-F failed me.
These super-high efficiency gas turbines are not 'pure' gas turbines, but so-called combined cycle plants. Basically you first have a 'normal' gas turbine driving a generator (which, by itself, maybe gives you ~45% efficiency), but then you take the host exhaust of that gas turbine and use that to drive a secondary steam cycle driving another generator.
I'm not sure such a thing is doable in a closed Brayton cycle, at least I haven't read anything about anything like that.
An interesting thing with closed cycle Brayton is that instead of air you can use another fluid as the working fluid. Supercritical CO2, for instance, has some nice properties leading to extremely compact machinery. Of course there's an uphill battle in commercializing this technology; if you use air (or nitrogen) you can just adapt one of the many existing gas turbine cores with $zillions of R&D and decades of experience behind them.
[0] https://www.nytimes.com/2017/03/29/business/westinghouse-tos...
[1] https://www.usnews.com/news/business/articles/2022-07-18/ge-...