People have jobs, learn, keep ties, and move on to do what they know elsewhere.

Talking about private sector, private contractor doing shaded activities for US clients is not the same as "Israel espionage". Israel is a country, does the article suggest evidence that Israel (or someone on its behalf) have done any espionage in US?

Qouting your comment from another thread: "The article is presenting a claim [you are, Israel espionage is not claimed in the article] which needs to be backed by sound evidence, like research papers [or any other evidence]. That's where the burden of proof lies, not on those who reject the claim on face value."

Https://news.ycombinator.com/item?id=20886710