We know how to test string theory but we lack the ability to generate sufficient energy to do so. We don't even know how to reliably test many of the theories generated by the social sciences. That's the difference between a robust science and a squishy one: effective methods for generating and testing hypotheses. String theory is part of the "generating" process. It makes falsifiable and (theoretically) testable predictions. There's no reason that experimental results are required for that process, so long as everyone is clear about the hypotheses not being experimentally supported yet. The separation between theoretical and experimental physics is particularly necessary because testing quantum physics hypotheses involves multi-billion dollar investments in particle colliders. Yet once that investment is made, the experiments are effective at testing the theories and the theories are effective at being tested by experiments. You can't say the same about the squishier end of the scientific spectrum.
"Generate hypothesis with CB and present experimental data that is mostly irrelevant to it" seems to be a good recipe for getting Nature papers, actually.
Supersymmetry and string theory have long been presented to the general public as "theoretical physics awaiting experimental validation." See, e.g., the Elegant Universe. Hell the fact that the LHC hasn't reported a new particle where most supersymmetry theorists expected one to be has prompted a rush towards moving goalposts to keep supersymmetry alive. That's not the sign of a robust theory.
You're conflating particle physics (which does need "multi-billion dollar investments") with quantum physics which sometimes only needs well designed table top experiments.