A force is not an ontology detector.

London and Casimir forces are real. The claim that they uniquely reveal a quantized vacuum is much stronger than the measurements warrant.

Stochastic electrodynamics keeps Maxwell–Lorentz dynamics and introduces a Lorentz-invariant random electromagnetic background. Within that explicitly classical program, zero-point correlations have been used to recover important dispersion and Casimir-type results. Whether the program succeeds universally is separate from the logical point: the observed attraction does not uniquely select field quantization.

Even within mainstream quantum theory, Robert Jaffe emphasized that Casimir forces can be formulated as interactions among charges and currents without treating measured force as direct evidence that vacuum zero-point energy is physically “real” in the naïve sense.

If two inequivalent ontological stories produce the same force law, the force law did not choose between them.

What the reconstruction must earn

Correct coefficients, retardation crossover, material response, geometry dependence, finite temperature and fluctuation statistics. No free victory. But equally: no free quantum victory merely because the successful conventional calculation is written with operators.

Read

Boyer, Random electrodynamics (1975)
Jaffe, The Casimir Effect and the Quantum Vacuum