There is no evidence to suggest that string theorists designed the theory to be untestable.
After this much time and that much work, how is it possible for a physics theory to not have a single testable/falsifiable prediction without it being intentional? It has been over 80 years. [https://en.m.wikipedia.org/wiki/History_of_string_theory].
The evidence is in the absence.
That proves it!
I mean, you should prove they didnt. If that sounds unreasonable we've made progress. Prove we didn't?
Ill let myself out