I agree with you in principle, but the combination of the base rate for "26-year-olds redefining reality" being so low and the consequences being not nearly as

I agree with you in principle, but the combination of the base rate for "26-year-olds redefining reality" being so low and the consequences being not nearly as dire as you make out mean I stand by my claim, at least for the case of heuristics on how to identify dangerous cults. With regards to the Einstein bit, per my above comment I still think that skepticism of GR was perfectly rational right up until it got an empirical demonstration. And it's not like the consequences for disbelieving Einstein prior to 1919 were that dire: the people who embraced relativity before then didn't see any major benefit for doing so, nor did it hurt society all that much (there was no technology between 1915 and 1919 that could've taken advantage of it).