The Overton window has not shifted, at least not among rank-and-file tech workers. There was very loud and vocal internal opposition to building and selling weapons[0]. They all lost the argument in the boardrooms because the US government writes very big checks. But I am told they are very much still around.

CEOs are bound to sociopathically amoral behavior - not by the law, but by the Pareto-optimal behavior of the job market for executives. The law obligates you to act in the interests of the shareholders, but it does not mandate[1] that Line Go Up. That is a function of a specific brand of shareholder that fires their CEOs every 18 months until the line goes up.

In 2007, Big Tech had plenty of the consumer market to conquer, so they could afford to pretend to be opposed to selling to the military. But the game they were playing was always going to end with them selling to the military. Once they were entrenched they could ignore the no-longer-useful-to-us-right-now dissenters, change their politics on a dime, and go after the "real money".

[0] Several of the sibling comments are mentioning hypothetical scenarios involving dual-use technologies or obfuscated purposes. Those are also relevant, but not the whole story.

[1] There are plenty of arguments a CEO could use to defend against a shareholder lawsuit that they did not take a particularly short-sighted action. Notably, that most line-go-up actions tend to be bad long-term decisions. You're allowed to sell low-risk investments.