Einstein disavowed operationalism

Czech physicist Lumo posts an anti-philosophy rant including:

not even Einstein considered himself a revolutionary who wanted to negate the work of Isaac Newton and others. Instead, Einstein considered relativity to be an improvement or clarification of Newton's and Maxwell's theories and he has explicitly stated this point of view several times.

On the other hand, it is true that Einstein has obviously brought new important ideas to physics, including new philosophical principles how the truth should be searched for. In particular, he realized that certain seemingly objective quantities or properties – such as the simultaneity of two events – don't have to be objective or don't have to "exist". He was the first one to fully realize that physics is only obliged to discuss properties of Nature that can actually be operationally measured, at least in principle. The simultaneity of two events and other things that became "relative" in the theory of relativity can't be established by objective operational tests so they may be subjective. Einstein was the first major practitioner of positivism in physics. ...

Einstein never accepted quantum mechanics ...

No, Einstein got relativistic simultaneity entirely from Poincare, and only credited Newton and Maxwell as a way of avoiding crediting Lorentz and Poincare. More importantly, Einstein did not have the opinion that physics is limited to what can be operationally measured. The main reason he did not accept quantum mechanics was its emphasis on what can be operationally measured, and he argued that the theory was incomplete if it only did that. He spent the last 30 years of his life pursuing unified field theories that had no relevance to operational measurements.

When Bohr and others debated Einstein, they sometimes argued that they were influenced to operational measurement by relativity, but Einstein denied that view, claiming that relativity was driven by big principles, and not operationalism. Positivism was popular in the 1930s, but Einstein was not a positivist. Even today, positivism is considered dead.

Lumo acknowledges that Einstein "couldn't fully break up from the straitjacket of classical physics" and quotes this conversation:

Heisenberg: "One cannot observe the electron orbits inside the atom. [...] but since it is reasonable to consider only those quantities in a theory that can be measured, it seemed natural to me to introduce them only as entities, as representatives of electron orbits, so to speak."

Einstein: "But you don't seriously believe that only observable quantities should be considered in a physical theory?"

"I thought this was the very idea that your Relativity Theory is based on?" Heisenberg asked in surprise.

"Perhaps I used this kind of reasoning," replied Einstein, "but it is nonsense nevertheless. [...] In reality the opposite is true: only the theory decides what can be observed."

(translated from "Der Teil und das Ganze" by W. Heisenberg)

This clearly shows that Heisenberg was the positivist, not Einstein. Perhaps Heisenberg did not realize that the positivist aspects of relativity were due to Lorentz and Poincare, not Einstein.

Einstein is praised today largely because of the perception that he ignored experiment and instead applied grand ideas to say how the world works. If Einstein were really an operationalist, then he would not be such a hero to the string theorists and others with untestable theories. This is all detailed in my book.